├── .github
    ├── issue_template.md
    └── pull_request_template.md
├── C++
    ├── 01. Introduction
    │   ├── Arrays Introduction.cpp
    │   ├── Basic Data Types.cpp
    │   ├── Conditional Statements.cpp
    │   ├── For Loop.cpp
    │   ├── Functions.cpp
    │   ├── Input and Output.cpp
    │   ├── Pointer.cpp
    │   ├── Say_Hello_World_With_C++.cpp
    │   └── Variable Sized Arrays.cpp
    ├── 02. Strings
    │   ├── Attribute Parser.cpp
    │   ├── StringStream.cpp
    │   └── Strings.cpp
    ├── 03. Classes
    │   ├── BoxIt.cpp
    │   ├── Class.cpp
    │   └── Structs.cpp
    ├── 04. STL
    │   ├── Deque-STL.cpp
    │   ├── Lower Bound-STL.cpp
    │   ├── Maps-STL.cpp
    │   ├── Sets-STL.cpp
    │   ├── Vector Erase STL.cpp
    │   └── Vector-Sort.cpp
    ├── 05. Inheritance
    │   ├── Accessing Inherited Functions.cpp
    │   ├── Multi_Level_Inheritance.cpp
    │   └── Rectangle Area.cpp
    ├── 06. Debugging
    │   ├── CPP Exception Handling.cpp
    │   └── Overloading Ostream Operator.cpp
    ├── 07. Other Concepts
    │   └── Operator Overloading.cpp
    └── STL
    │   └── vector-sort.cpp
├── CODE_OF_CONDUCT.md
├── CONTRIBUTING.md
├── Java
    ├── 01. Introduction
    │   ├── Currency Formatter.java
    │   ├── Java Datatypes.java
    │   ├── Java Date and Time.java
    │   ├── Java If-Else.java
    │   ├── Java Int to String.java
    │   ├── Java Loops II.java
    │   ├── Java Static initializer block.java
    │   ├── Java Stdin and Stdout I.java
    │   ├── Java Stdin and Stdout II.java
    │   └── Welcome To Java.java
    ├── 02. Strings
    │   ├── Java Anagrams.java
    │   ├── Java Substring.java
    │   └── Java_Int_to_String.java
    ├── 03. BigNumber
    │   └── dummy.java
    ├── 04. Data Structures
    │   ├── Java 1D Array.java
    │   └── Java Stack.java
    ├── 05.Java_Sort
    │   └── Java_sort.java
    ├── Object Oriented Programming
    │   ├── Java Abstract Class.java
    │   ├── Java Inheritance I.java
    │   ├── Java Inheritance II.java
    │   ├── Java Interface.java
    │   └── Java Method Overriding.java
    └── sorting
    │   ├── bubblesort.java
    │   ├── countingsort.java
    │   ├── insertionsort.java
    │   └── selectionsort.java
├── LICENSE
├── Problem Solving
    ├── Algorithms
    │   ├── Bit Manipulation
    │   │   └── Maximizing_XOR.cpp
    │   ├── Dynamic Programming
    │   │   ├── Equal
    │   │   │   └── Equal.cpp
    │   │   ├── Stock Maximize
    │   │   │   └── Stock Maximize.cpp
    │   │   └── The Coin Change Problem
    │   │   │   └── The Coin Change Problem.cpp
    │   ├── Recursion
    │   │   ├── Crossword Puzzle
    │   │   │   └── dummy.py
    │   │   ├── Recursive Digit Sum
    │   │   │   ├── Recursive Digit Sum.cpp
    │   │   │   ├── Recursive Digit Sum.java
    │   │   │   └── Recursive Digit Sum.py
    │   │   └── The Power Sum
    │   │   │   ├── dummy.cpp
    │   │   │   └── power.py
    │   └── Searching
    │   │   └── Array Solution
    │   │       └── Array Solution.cpp
    └── Data Structures
    │   ├── Array
    │       └── Left Rotation
    │       │   └── Left Rotation.java
    │   └── Stacks
    │       └── Balanced Brackets
    │           └── Balanced Brackets.cpp
├── Python
    ├── 01. Introduction
    │   ├── Loops.py
    │   ├── Python Division.py
    │   ├── Python If-Else.py
    │   └── Write a function.py
    ├── 02. Basic Data Types
    │   ├── Find the Runner-Up Score.py
    │   ├── Finding The Percentage.py
    │   └── List Comprehensions.py
    ├── 03. Strings
    │   ├── StringValidators.py
    │   ├── dummy.py
    │   └── sWAP_cASE.py
    ├── 04. Sets
    │   └── No Idea!.py
    └── Debugging
    │   └── Words Score.py
├── README.md
└── SQL
    ├── 1. BASIC SELECT
        ├── 01. Revising the Select Query I.sql
        ├── 02. Revising the Select Query II.sql
        ├── 03. Select All.sql
        ├── 04. Select By ID.sql
        ├── 05. Japanese Cities' Attributes.sql
        ├── 06. Japanese Cities' Names.sql
        ├── 07. Weather Observation Station 1.sql
        ├── 08. Weather Observation Station 3.sql
        ├── 09. Weather Observation Station 4.sql
        ├── 10. Weather Observation Station 5.sql
        ├── 11. Weather Observation Station 6.sql
        ├── 12. Weather Observation Station 7.sql
        ├── 13. Weather Observation Station 8.sql
        ├── 14. Weather Observation Station 9.sql
        ├── 15. Weather Observation Station 10.sql
        ├── 16. Weather Observation Station 11.sql
        ├── 17. Weather Observation Station 12.sql
        ├── 18. Higher Than 75 Marks.sql
        ├── 19. Employee Names.sql
        └── 20. Employee Salaries.sql
    ├── 2. ADVANCED SELECT
        ├── 01.Type of Triangle.sql
        ├── 02. The PADS.sql
        ├── 03. Occupations.sql
        ├── 04. Binary Tree Nodes.sql
        └── 05. New Companies.sql
    ├── 3. AGGREGATION
        ├── 01.Revising Aggregations - The Count Function.sql
        ├── 02. Revising Aggregations - The Sum Function.sql
        ├── 03. Revising Aggregations - Averages.sql
        ├── 04. Average Population.sql
        ├── 05. Japan Population.sql
        ├── 06. Population Density Difference.sql
        ├── 07. The Blunder.sql
        ├── 08. Top Earners.sql
        ├── 09. Weather Observation Station 2.sql
        ├── 10. Weather Observation Station 13.sql
        ├── 11. Weather Observation Station 14.sql
        ├── 12. Weather Observation Station 15.sql
        ├── 13. Weather Observation Station 16.sql
        ├── 14. Weather Observation Station 17.sql
        ├── 15. Weather Observation Station 18.sql
        ├── 16. Weather Observation Station 19.sql
        └── 17. Weather Observation Station 20.sql
    ├── 4. BASIC JOIN
        ├── 01. Population Census.sql
        ├── 02. African Cities.sql
        ├── 03. Average Population of Each Continent.sql
        ├── 04. The Report.sql
        ├── 05. Top Competitors.sql
        ├── 06. Ollivander's Inventory.sql
        ├── 07. Challenges.sql
        └── 08. Contest Leaderboard.sql
    ├── 5. ADVANCED JOIN
        ├── 01. SQL Project Planning.sql
        ├── 02. SQL Symmetric Pairs.sql
        ├── 03. 15 Days of Learning SQL.sql
        └── Interviews.sql
    └── 6. ALTERNATIVE QUERIES
        ├── 01. Draw The Triangle 1.sql
        └── 02. Draw The Triangle 2.sql


/.github/issue_template.md:
--------------------------------------------------------------------------------
 1 | ### Hackerrank problem link
 2 | 
 3 | Provide your hackerrank problem link here.
 4 | 
 5 | ### Language
 6 | 
 7 | If you are contributing to data structures or algorithms problem, which programming language will you use?
 8 | 
 9 | ### Issue Checklist
10 | 
11 | * [ ] Have you checked that the hackerrank problem you are raising is not already present in the repo?
12 | * [ ] Have you checked that the hackerrank problem you are raising is not raised by or assigned to another contributor?
13 | * [ ] Have you read the [CONTRIBUTING.md](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/CONTRIBUTING.md) file?
14 | 
15 | ### Any other Changes?
16 | 
17 | If you are raising an issue with some more changes, please provide the details here.
18 | 


--------------------------------------------------------------------------------
/.github/pull_request_template.md:
--------------------------------------------------------------------------------
 1 | ### Issue Number:
 2 | 
 3 | This submission closes #<!--Issue Number without giving space--> issue
 4 | 
 5 | ### Submissions Checklist:
 6 | 
 7 | <!-- Don't know how to mark a checkbox?
 8 | Use [x] for marking a checkbox with no space inside the brackets -->
 9 | 
10 | * [ ] This issue was assigned to you.
11 | * [ ] Have you followed the guidelines in [CONTRIBUTING.md](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/CONTRIBUTING.md)?
12 | * [ ] Have you checked there aren't other open [Pull Requests](https://github.com/Riddhi9570/HackerrankPracticeProblems/pulls) for the same hackerrank problem?
13 | * [ ] Have you successfully submitted your code in hackerrank?
14 | * [ ] Is your file name exactly same as the problem name of hackerrank, followed by the proper extension?
15 | * [ ] Have you ensured that you have put the files in appropriate folders? (Folders are made according to the subdomain of hackerrank practice problems).
16 | 
17 | ### Hackerrank Problem Link:
18 | 
19 | <!-- Provide your hacckerrank problem link here-->
20 | 
21 | ### Submitted Hackerrank Solution Link:
22 | 
23 | <!-- Go to your hackerrank problem, select your "submission" and go to "view results". Copy the URL and provide the submission link here-->
24 | 
25 | ### Any other changes you made or something you would like to mention?
26 | 
27 | <!-- Write NA if not applicable-->
28 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/Arrays Introduction.cpp:
--------------------------------------------------------------------------------
 1 | // below is the solution to arrays introduction problem: https://www.hackerrank.com/challenges/arrays-introduction/problem?isFullScreen=true
 2 | // Score:10
 3 | // Difficulty: Easy
 4 | #include <iostream>
 5 | 
 6 | using namespace std;
 7 | 
 8 | int main(int argc, char const *argv[])
 9 | {
10 |     int N;
11 |     cin>>N; //taking N as input
12 |     int arr[N]; //declaring an array of size N
13 |     for(int i=0;i<N;i++){
14 |         cin>>arr[i]; //taking input the elements of the array
15 |     }
16 |     for(int i=N-1;i>=0;i--){
17 |         cout<<arr[i]<<" ";
18 |     }
19 |     return 0;
20 | }
21 | 


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/C++/01. Introduction/Basic Data Types.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : Basic Data Types 
 2 | // Problem Link : https://www.hackerrank.com/challenges/c-tutorial-basic-data-types/problem?isFullScreen=true
 3 | // Language: CPP
 4 | // Difficulty: Easy
 5 | // Max Score: 10
 6 | // ..............................................................................................................................................
 7 | // Input Format of this Problem:
 8 | //              Input consists of the following space-separated values: int, long, char, float, and double, respectively.
 9 | 
10 | // Output format of this Problem:
11 | //              Print each element on a new line in the same order it was received as input.
12 | //              Note that the floating point value should be correct up to 3 decimal places and the double to 9 decimal places.
13 | 
14 | //  ..............................................................................................................................................
15 | // Here is the Code for this Problem:
16 | 
17 | 
18 | #include <iostream>
19 | #include <cstdio>
20 | using namespace std;
21 | 
22 | int main() {
23 |         int a;
24 |         long long int b;
25 |         char c;
26 |         float d;
27 |         double e;
28 | 
29 | scanf("%d %lld %c %f %lf",&a,&b,&c,&d,&e);
30 | printf("%d\n%lld\n%c\n%f\n%lf",a,b,c,d,e);
31 | 
32 | // you can also use the below code to take input and give output
33 |   
34 | // cin>>a>>b>>c>>d>>e;
35 | // cout<<a<<endl<<b<<endl<<c<<endl<<d<<endl<<e;
36 |   
37 |     return 0;
38 | }
39 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/Conditional Statements.cpp:
--------------------------------------------------------------------------------
 1 | // # Problem : https://www.hackerrank.com/challenges/c-tutorial-conditional-if-else/problem
 2 | // # Score : 10.0
 3 | // # Difficulty : Easy 
 4 | 
 5 | #include <bits/stdc++.h>
 6 | 
 7 | using namespace std;
 8 | 
 9 | //defines functions
10 | string ltrim(const string &);
11 | string rtrim(const string &);
12 | 
13 | 
14 | 
15 | int main()
16 | {
17 |     string n_temp;
18 |     //gets input as a string
19 |     getline(cin, n_temp);
20 | 
21 |     //trims all trailing whitespaces and gives integer form of input
22 |     int n = stoi(ltrim(rtrim(n_temp)));
23 | 
24 |     // Write your code here
25 |     // if-else if statements to check which number it is, else statement if it is greater than 9
26 |     
27 |     if(n==1){
28 |         cout << "one";
29 |     }
30 |     else if(n==2){
31 |         cout << "two";
32 |     }
33 |     else if(n==3){
34 |         cout << "three";
35 |     }
36 |     else if(n==4){
37 |         cout << "four";
38 |     }
39 |     else if(n==5){
40 |         cout << "five";
41 |     }
42 |     else if(n==6){
43 |         cout << "six";
44 |     }
45 |     else if(n==7){
46 |         cout << "seven";
47 |     }
48 |     else if(n==8){
49 |         cout << "eight";
50 |     }
51 |     else if(n==9){
52 |         cout << "nine";
53 |     }
54 |     else{
55 |         cout << "Greater than 9";
56 |     }
57 | 
58 |     return 0;
59 | }
60 | 
61 | string ltrim(const string &str) {
62 |     string s(str);
63 | 
64 |     s.erase(
65 |         s.begin(),
66 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
67 |     );
68 | 
69 |     return s;
70 | }
71 | 
72 | string rtrim(const string &str) {
73 |     string s(str);
74 | 
75 |     s.erase(
76 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
77 |         s.end()
78 |     );
79 | 
80 |     return s;
81 | }
82 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/For Loop.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link :https://www.hackerrank.com/challenges/c-tutorial-for-loop/problem
 2 | //Difficulty : Easy
 3 | //Max Score:10
 4 | #include<bits/stdc++.h>
 5 | using namespace std;
 6 | int main() {
 7 |     // taking input of a ,b 
 8 |     int a,b;   
 9 |     cin>>a>>b;
10 |     // initializing vector of strings named hashmap to store word value of 1 to 9 int values 
11 |     vector<string>hashmap{"one","two","three","four","five","six","seven","eight","nine"};
12 |     // making a for loop from a to b and checking if i is between i to 9 then preint corresponding word value of i 
13 |     // if i is greater than i then check if i is even or odd.
14 |     for(int i=a;i<=b;i++)
15 |     {
16 |         if(1<=i and i<=9)
17 |         {
18 |             cout<<hashmap[i-1]<<endl;
19 |         }
20 |         else
21 |         {
22 |             if((i&1)==0){
23 |                 cout<<"even"<<endl;
24 |             }
25 |             else
26 |             {
27 |                 cout<<"odd"<<endl;
28 |             }
29 |         }
30 |     }
31 |     return 0;
32 | }
33 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/Functions.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : Functions 
 2 | // Problem Link : https://www.hackerrank.com/challenges/c-tutorial-functions/problem
 3 | // Difficulty: Easy
 4 | // Max Score: 10
 5 | #include <iostream>
 6 | using namespace std;
 7 | 
 8 | int max_of_four(int a, int b, int c, int d) {
 9 |     return max(a, max(b, max(c, d)));
10 | }
11 | 
12 | int main() {
13 |     int a, b, c, d;
14 |     cin>>a>>b>>c>>d;
15 |     int ans = max_of_four(a, b, c, d);
16 |    cout<<ans;
17 |     
18 |     return 0;
19 | }


--------------------------------------------------------------------------------
/C++/01. Introduction/Input and Output.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/cpp-input-and-output/problem
 2 | // Score: 5.0
 3 | // Difficulty : Easy
 4 | 
 5 | #include <iostream>
 6 | using namespace std;
 7 | 
 8 | int main() {
 9 |     int a,b,c;
10 |     cin>>a>>b>>c;
11 |     cout<<(a+b+c);  
12 |     return 0;
13 | }
14 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/Pointer.cpp:
--------------------------------------------------------------------------------
 1 | // # Problem : https://www.hackerrank.com/challenges/c-tutorial-pointer/problem
 2 | // # Score : 10.0
 3 | // # Difficulty : Easy
 4 | 
 5 | #include <stdio.h>
 6 | #include <stdlib.h>
 7 | 
 8 | void update(int *a, int *b)
 9 | {
10 |     int temp_a = *a;
11 |     int temp_b = *b;
12 |     *a = temp_a + temp_b;
13 |     *b = abs(temp_a - temp_b);
14 | }
15 | 
16 | int main()
17 | {
18 |     int a, b;
19 |     int *pa = &a, *pb = &b;
20 | 
21 |     scanf("%d %d", &a, &b);
22 |     update(pa, pb);
23 |     printf("%d\n%d", a, b);
24 | 
25 |     return 0;
26 | }
27 | 


--------------------------------------------------------------------------------
/C++/01. Introduction/Say_Hello_World_With_C++.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/cpp-hello-world/problem
 2 | // Score: 5.0
 3 | // Difficulty : Easy
 4 | 
 5 | #include <iostream>
 6 | #include <cstdio>
 7 | using namespace std;
 8 | 
 9 | int main()
10 | {
11 |     cout << "Hello, World!";
12 |     return 0;
13 | }


--------------------------------------------------------------------------------
/C++/01. Introduction/Variable Sized Arrays.cpp:
--------------------------------------------------------------------------------
 1 | //Hackerrank Problem link: https://www.hackerrank.com/challenges/variable-sized-arrays/problem
 2 | //Score: 30.0
 3 | //Difficulty level: Easy
 4 | 
 5 | #include <cmath>
 6 | #include <cstdio>
 7 | #include <vector>
 8 | #include <iostream>
 9 | #include <algorithm>
10 | using namespace std;
11 | 
12 | 
13 | int main() { 
14 |     int n,q;
15 |     cin>>n>>q;
16 |     vector<vector<int>> varlength;
17 |     for(int i=0;i<n;i++){
18 |         int len;
19 |         cin>>len;
20 |         vector<int> curind(len);
21 |         for(int j=0;j<len;j++){
22 |             cin>>curind[j];
23 |         }
24 |         varlength.push_back(curind);
25 |     }
26 |     while(q--){
27 |         int outerind,innerind;
28 |         cin>>outerind>>innerind;
29 |         cout<<varlength[outerind][innerind]<<"\n";
30 |     }
31 |     return 0;
32 | }
33 | 


--------------------------------------------------------------------------------
/C++/02. Strings/Attribute Parser.cpp:
--------------------------------------------------------------------------------
 1 | //Problem Statement- https://www.hackerrank.com/challenges/attribute-parser/problem
 2 | //Score- 35
 3 | //Difficuly- Medium
 4 | 
 5 | 
 6 | 
 7 | 
 8 | #include <cmath>
 9 | #include <cstdio>
10 | #include <vector>
11 | #include <iostream>
12 | #include <algorithm>
13 | using namespace std;
14 | #include <bits/stdc++.h>
15 | 
16 | 
17 | 
18 | int main() {
19 |     
20 | int n, q,i;
21 | cin>>n>>q;
22 | string temp;
23 | vector<string> hrml;
24 | vector<string> quer;
25 | cin.ignore();
26 | for(i=0;i<n;i++)
27 | {
28 |     getline(cin,temp);
29 |     hrml.push_back(temp);
30 | }
31 | for(i=0;i<q;i++)
32 | {
33 |     getline(cin,temp);
34 |     quer.push_back(temp);
35 | }
36 | map<string, string> m;
37 | vector<string> tag;
38 | for(i=0;i<n;i++)
39 | {
40 |     temp=hrml[i];
41 |     temp.erase(remove(temp.begin(), temp.end(), '\"' ),temp.end());
42 |     temp.erase(remove(temp.begin(), temp.end(), '>' ),temp.end());
43 |     if(temp.substr(0,2)=="</")
44 |     {
45 |         tag.pop_back();
46 |     }
47 |     else
48 |     {
49 |         stringstream ss;
50 |         ss.str("");
51 |         ss<<temp;
52 |         string t1,p1,v1;
53 |         char ch;
54 |         ss>>ch>>t1>>p1>>ch>>v1;
55 |         string temp1="";
56 |         if(tag.size()>0)
57 |         {
58 |             temp1=*tag.rbegin();
59 |             temp1=temp1+"."+t1;
60 |         }
61 |         else
62 |             temp1=t1;
63 |         tag.push_back(temp1);
64 |         m[*tag.rbegin()+"~"+p1]=v1;
65 |         while(ss)
66 |         {
67 |             ss>>p1>>ch>>v1;
68 |             m[*tag.rbegin()+"~"+p1]=v1;
69 |         }
70 |     }
71 | }
72 | for(i=0;i<q;i++){
73 |     if (m.find(quer[i]) == m.end())
74 |         cout << "Not Found!\n";
75 |     else
76 |         cout<<m[quer[i]]<<endl;
77 | }
78 | return 0;
79 |         
80 |     }
81 | 
82 | 
83 | 


--------------------------------------------------------------------------------
/C++/02. Strings/StringStream.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link :https://www.hackerrank.com/challenges/c-tutorial-stringstream/problem?isFullScreen=true
 2 | // Score: 10
 3 | // Difficulty: Easy
 4 | 
 5 | #include <sstream>
 6 | #include <vector>
 7 | #include <iostream>
 8 | using namespace std;
 9 | 
10 | vector<int> parseInts(string str) {
11 | 	// Complete this function
12 |     stringstream ss(str);
13 |     vector<int>ans;
14 |     string t;
15 |     while(getline(ss,t,','))
16 |     {
17 |         ans.push_back(stoi(t));
18 |     } 
19 |     return ans;   
20 | }
21 | 
22 | int main() {
23 |     string str;
24 |     cin >> str;
25 |     vector<int> integers = parseInts(str);
26 |     for(int i = 0; i < integers.size(); i++) {
27 |         cout << integers[i] << "\n";
28 |     }
29 |     
30 |     return 0;
31 | }
32 | 


--------------------------------------------------------------------------------
/C++/02. Strings/Strings.cpp:
--------------------------------------------------------------------------------
 1 | // problem: https://www.hackerrank.com/challenges/c-tutorial-strings/submissions/code/293651711
 2 | // Score: 10.0
 3 | // Difficulty: Easy
 4 | 
 5 | #include <iostream>
 6 | #include <string>
 7 | using namespace std;
 8 | 
 9 | int main()
10 | {
11 | 
12 |     string a;
13 |     string b;
14 | 
15 |     cin >> a;
16 |     cin >> b;
17 | 
18 |     cout << a.length() << " " << b.length() << endl;
19 |     string c = a + b;
20 |     cout << c << endl;
21 |     string temp;
22 |     temp = a[0];
23 |     a[0] = b[0];
24 |     b[0] = temp[0];
25 |     cout << a << " " << b;
26 | 
27 |     return 0;
28 | }


--------------------------------------------------------------------------------
/C++/03. Classes/BoxIt.cpp:
--------------------------------------------------------------------------------
  1 | // Program Link: https://www.hackerrank.com/challenges/box-it/problem?isFullScreen=true
  2 | // Problem: Box It!
  3 | // Language: C++
  4 | // Subdomain: Class
  5 | // Max Score: 30
  6 | // Difficulty: Easy
  7 | 
  8 | #include <bits/stdc++.h>
  9 | 
 10 | using namespace std;
 11 | class Box
 12 | {
 13 |     int l, b, h;
 14 | 
 15 | public:
 16 |     Box()
 17 |     {
 18 |         l = 0;
 19 |         b = 0;
 20 |         h = 0;
 21 |     }
 22 |     Box(int length, int breadth, int height)
 23 |     {
 24 |         l = length;
 25 |         b = breadth;
 26 |         h = height;
 27 |     }
 28 |     Box(Box &B)
 29 |     {
 30 |         l = B.l;
 31 |         b = B.b;
 32 |         h = B.h;
 33 |     }
 34 | 
 35 |     int getLength()
 36 |     {
 37 |         return l;
 38 |     }
 39 |     int getBreadth()
 40 |     {
 41 |         return b;
 42 |     }
 43 |     int getHeight()
 44 |     {
 45 |         return h;
 46 |     }
 47 |     long long CalculateVolume()
 48 |     {
 49 |         return (long long)l * b * h;
 50 |     }
 51 |     bool operator<(const Box &b2)
 52 |     {
 53 |         Box b1;
 54 |         if (l < b2.l || (b < b2.b && l == b2.l) || (h < b2.h && b == b2.b && l == b2.l))
 55 |         {
 56 |             return true;
 57 |         }
 58 | 
 59 |         return false;
 60 |     }
 61 |     friend ostream &operator<<(ostream &os, Box &B);
 62 | };
 63 | ostream &operator<<(ostream &os, Box &B)
 64 | {
 65 |     os << B.l << " " << B.b << " " << B.h;
 66 |     return os;
 67 | }
 68 | 
 69 | void check2()
 70 | {
 71 |     int n;
 72 |     cin >> n;
 73 |     Box temp;
 74 |     for (int i = 0; i < n; i++)
 75 |     {
 76 |         int type;
 77 |         cin >> type;
 78 |         if (type == 1)
 79 |         {
 80 |             cout << temp << endl;
 81 |         }
 82 |         if (type == 2)
 83 |         {
 84 |             int l, b, h;
 85 |             cin >> l >> b >> h;
 86 |             Box NewBox(l, b, h);
 87 |             temp = NewBox;
 88 |             cout << temp << endl;
 89 |         }
 90 |         if (type == 3)
 91 |         {
 92 |             int l, b, h;
 93 |             cin >> l >> b >> h;
 94 |             Box NewBox(l, b, h);
 95 |             if (NewBox < temp)
 96 |             {
 97 |                 cout << "Lesser\n";
 98 |             }
 99 |             else
100 |             {
101 |                 cout << "Greater\n";
102 |             }
103 |         }
104 |         if (type == 4)
105 |         {
106 |             cout << temp.CalculateVolume() << endl;
107 |         }
108 |         if (type == 5)
109 |         {
110 |             Box NewBox(temp);
111 |             cout << NewBox << endl;
112 |         }
113 |     }
114 | }
115 | 
116 | int main()
117 | {
118 |     check2();
119 | }


--------------------------------------------------------------------------------
/C++/03. Classes/Class.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link: https://www.hackerrank.com/challenges/c-tutorial-class/problem
 2 | // Difficulty: Easy
 3 | // Max Score: 10
 4 | 
 5 | #include <iostream>
 6 | #include <sstream>
 7 | using namespace std;
 8 | 
 9 | class Student {
10 |     int age;
11 |     int standard;
12 |     string first_name;
13 |     string last_name;
14 | 
15 |    public:
16 |     void set_age(int age_) { age = age_; }
17 | 
18 |     void set_standard(int standard_) { standard = standard_; }
19 | 
20 |     void set_first_name(string first_name_) { first_name = first_name_; }
21 | 
22 |     void set_last_name(string last_name_) { last_name = last_name_; }
23 | 
24 |     int get_age() { return age; }
25 | 
26 |     int get_standard() { return standard; }
27 | 
28 |     string get_first_name() { return first_name; }
29 | 
30 |     string get_last_name() { return last_name; }
31 | 
32 |     string to_string() {
33 |         string age_ = std::to_string(age);
34 |         string standard_ = std::to_string(standard);
35 |         string result =
36 |             age_ + "," + first_name + "," + last_name + "," + standard_;
37 |         return result;
38 |     }
39 | };
40 | 
41 | int main() {
42 |     int age, standard;
43 |     string first_name, last_name;
44 | 
45 |     cin >> age >> first_name >> last_name >> standard;
46 | 
47 |     Student st;
48 |     st.set_age(age);
49 |     st.set_standard(standard);
50 |     st.set_first_name(first_name);
51 |     st.set_last_name(last_name);
52 | 
53 |     cout << st.get_age() << "\n";
54 |     cout << st.get_last_name() << ", " << st.get_first_name() << "\n";
55 |     cout << st.get_standard() << "\n";
56 |     cout << "\n";
57 |     cout << st.to_string();
58 | 
59 |     return 0;
60 | }


--------------------------------------------------------------------------------
/C++/03. Classes/Structs.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link: https://www.hackerrank.com/challenges/c-tutorial-struct/problem
 2 | // Difficulty: Easy
 3 | // Max Score: 10
 4 | 
 5 | #include <cmath>
 6 | #include <cstdio>
 7 | #include <vector>
 8 | #include <iostream>
 9 | #include <algorithm>
10 | using namespace std;
11 | 
12 | struct Student {
13 |   int age;
14 |   string first_name;
15 |   string last_name;
16 |   int standard;
17 | };
18 | 
19 | int main() {
20 |     Student st;
21 |     
22 |     cin >> st.age >> st.first_name >> st.last_name >> st.standard;
23 |     cout << st.age << " " << st.first_name << " " << st.last_name << " " << st.standard;
24 |     
25 |     return 0;
26 | }
27 | 


--------------------------------------------------------------------------------
/C++/04. STL/Deque-STL.cpp:
--------------------------------------------------------------------------------
 1 | // # Problem : https://www.hackerrank.com/challenges/deque-stl/problem?isFullScreen=false
 2 | // # Score : 50
 3 | // # Difficulty : Medium
 4 | 
 5 | #include <iostream>
 6 | #include <deque> 
 7 | using namespace std;
 8 | 
 9 | void printKMax(int arr[], int n, int k){
10 | 	//Write your code here.
11 |     
12 |     //variable for the max element in the current k elements
13 |     int maxim = 0;
14 |     
15 |     //create a deque to see current k elements
16 |     deque<int> curr;
17 |     
18 |     //get first k elements and put them in the deque
19 |     for(int i=0;i<k;i++){
20 |         curr.push_back(arr[i]);
21 |         if(arr[i]>maxim){
22 |             maxim = arr[i];
23 |         }
24 |     }
25 |     
26 |     cout << maxim << " ";
27 |     
28 |     int i = k;
29 |     while(i<n){
30 |         //gets current popped element
31 |         int front = curr.front();
32 |         
33 |         //if we removed the max element, we need to find the new max with iteration
34 |         if(front==maxim){
35 |             maxim = 0;
36 |             for(int j=i;j>i-k;j--){
37 |                 if(arr[j]>maxim){
38 |                     maxim = arr[j];
39 |                 }
40 |             }
41 |         }
42 |         
43 |         //remove last element and add current element
44 |         curr.pop_front();
45 |         curr.push_back(arr[i]);
46 |         
47 |         //checks  if current added element is greater than the current max
48 |         if(arr[i]>maxim){
49 |             maxim = arr[i];
50 |         }
51 |         
52 |         //prints the current max element
53 |         cout << maxim << " ";
54 |         
55 |         //increments  the current index we are on
56 |         i++;
57 |     }
58 |     
59 |     cout << endl;
60 |     
61 | }
62 | 
63 | int main(){
64 |   
65 | 	int t;
66 | 	cin >> t;
67 | 	while(t>0) {
68 | 		int n,k;
69 |     	cin >> n >> k;
70 |     	int i;
71 |     	int arr[n];
72 |     	for(i=0;i<n;i++)
73 |       		cin >> arr[i];
74 |     	printKMax(arr, n, k);
75 |     	t--;
76 |   	}
77 |   	return 0;
78 | }
79 | 


--------------------------------------------------------------------------------
/C++/04. STL/Lower Bound-STL.cpp:
--------------------------------------------------------------------------------
 1 | 
 2 | /*
 3 | -- # Problem Link : https://www.hackerrank.com/challenges/cpp-lower-bound/problem?isFullScreen=true
 4 | -- # Problem : Lower Bound-STL
 5 | -- # Language : C++
 6 | -- # Subdomain : STL
 7 | -- # Max Score : 15
 8 | -- # Difficulty : Easy
 9 | */
10 | 
11 | #include <cmath>
12 | #include <cstdio>
13 | #include <vector>
14 | #include <iostream>
15 | #include <algorithm>
16 | using namespace std;
17 | 
18 | 
19 | int main() {
20 |     /* Enter your code here. Read input from STDIN. Print output to STDOUT */     int n;
21 |     vector<int> vec;
22 |     cin >> n;
23 |     for (int i = 0; i < n; i++) {
24 |         int temp;
25 |         cin >> temp;
26 |         vec.push_back(temp);
27 |     }
28 |     int q;
29 |     cin >> q;
30 |     for (int i = 0; i < q; i++) {
31 |         int temp;
32 |         cin >> temp;
33 |         vector<int>::iterator iter;
34 |         iter = lower_bound(vec.begin(), vec.end(), temp);
35 |         if (*(iter + 1) == temp || *iter == temp)
36 |             cout << "Yes " << iter - vec.begin() + 1 << endl;
37 |         else
38 |             cout << "No " << iter - vec.begin() + 1 << endl;
39 |     }
40 |     return 0;
41 | 
42 | }
43 | 


--------------------------------------------------------------------------------
/C++/04. STL/Maps-STL.cpp:
--------------------------------------------------------------------------------
 1 | /*
 2 | -- # Problem Link : https://www.hackerrank.com/challenges/cpp-maps/problem?isFullScreen=true
 3 | -- # Problem : Maps-STL
 4 | -- # Language : C++
 5 | -- # Subdomain : STL
 6 | -- # Max Score : 15
 7 | -- # Difficulty : Easy
 8 | */
 9 | 
10 | #include <cmath>
11 | #include <cstdio>
12 | #include <vector>
13 | #include <iostream>
14 | #include <set>
15 | #include <map>
16 | #include <algorithm>
17 | using namespace std;
18 | 
19 | int main()
20 | {
21 |     ios::sync_with_stdio(0);
22 |     cin.tie(0);
23 | 
24 |     int a, b, c;
25 |     map<string, int> student;
26 |     cin >> a;
27 |     for (int i = 0; i < a; i++)
28 |     {
29 |         string s;
30 |         cin >> b;
31 |         if (b == 1)
32 |         {
33 |             cin >> s >> c;
34 |             map<string, int>::iterator iter;
35 |             iter = student.find(s); // if it donot find then it will store end location.
36 |             if (iter != student.end())
37 |             {
38 |                 iter->second += c;
39 |             }
40 |             else
41 |             {
42 |                 student[s] = c;
43 |             }
44 |         }
45 |         else if (b == 2)
46 |         {
47 |             cin >> s;
48 |             student.erase(s);
49 |         }
50 |         else
51 |         {
52 |             cin >> s;
53 |             map<string, int>::iterator it;
54 |             it = student.find(s);
55 |             if (it != student.end())
56 |             {
57 |                 cout << it->second << endl;
58 |             }
59 |             else
60 |             {
61 |                 cout << 0 << endl;
62 |             }
63 |         }
64 |     }
65 |     return 0;
66 | }


--------------------------------------------------------------------------------
/C++/04. STL/Sets-STL.cpp:
--------------------------------------------------------------------------------
 1 | /*
 2 | Problem Link : https://www.hackerrank.com/challenges/cpp-sets/problem?isFullScreen=true
 3 | Problem :Sets-STL
 4 | Category: C++ STL
 5 | Difficulty: Easy
 6 | Max Score: 15
 7 | */
 8 | #include <cmath>
 9 | #include <cstdio>
10 | #include <vector>
11 | #include <iostream>
12 | #include <set>
13 | #include <algorithm>
14 | using namespace std;
15 | 
16 | 
17 | int main() { 
18 |     int q;
19 |     cin>>q;
20 |     set<int>s;
21 |     for(int i=0;i<q;i++){
22 |         int y,x;
23 |         cin>>y>>x;
24 |         if(y==1){
25 |             s.insert(x);
26 |         }else if(y==2){
27 |             s.erase(x);
28 |         }else{
29 |             set<int>::iterator itr=s.find(x);
30 |             if(itr==s.end()){
31 |                 cout<<"No"<<"\n";
32 |             }else{
33 |                 cout<<"Yes"<<"\n";
34 |             }
35 |         }
36 |     }
37 |     return 0;
38 | }
39 | 


--------------------------------------------------------------------------------
/C++/04. STL/Vector Erase STL.cpp:
--------------------------------------------------------------------------------
 1 | 
 2 | // Problem: https://www.hackerrank.com/challenges/vector-erase/problem
 3 | // Score: 10
 4 | // Difficulty : Easy
 5 | 
 6 | #include <cmath>
 7 | #include <cstdio>
 8 | #include <vector>
 9 | #include <iostream>
10 | #include <algorithm>
11 | using namespace std;
12 | 
13 | 
14 | int main() {
15 |     int size,pos,start,end,n,i,a,j;
16 |     cin>>n;
17 |     vector<int>v;
18 |     for(i=0;i<n;i++)
19 |     {
20 |         cin>>a;
21 |         v.push_back(a);
22 |     }   
23 |     cin>>pos>>start>>end;
24 |     v.erase(v.begin()+(pos-1));
25 |     v.erase(v.begin()+start-1,v.begin()+end-1);
26 |     size=v.size();
27 |     cout<<size<<endl;
28 |     for(j=0;j<size;j++)
29 |     {
30 |         cout<<v[j]<<" ";
31 |     }
32 | return 0;
33 | }
34 | 
35 | 


--------------------------------------------------------------------------------
/C++/04. STL/Vector-Sort.cpp:
--------------------------------------------------------------------------------
 1 | // Problem: Vector-Sort 
 2 | // Problem link: https://www.hackerrank.com/challenges/vector-sort/problem?isFullScreen=true
 3 | // Language: CPP
 4 | // Difficulty: Easy
 5 | // Max Score: 10
 6 | // ......................................................................................................................................
 7 | 
 8 | // Vector : Vectors are sequence containers representing arrays that can change in size.
 9 | 
10 | // Declaration of a Vector: vector<int>v; (creates an empty vector of integers)
11 | 
12 | // Size of a vector: int size=v.size();
13 | 
14 | // Pushing an integer into a vector:  v.push_back(x);(where x is an integer.The size increases by 1 after this.)
15 | 
16 | // Popping the last element from the vector:  v.pop_back(); (After this the size decreases by 1)
17 | 
18 | // Sorting a vector:  sort(v.begin(),v.end()); (Will sort all the elements in the vector)
19 | 
20 | // .......................................................................................................................................
21 | 
22 | // Input Format :
23 | //                The first line of the input contains N ,where N is the number of integers. The next line contains  integers.
24 | 
25 | // Output Format : 
26 | //                Print the integers in the sorted order one by one in a single line followed by a space.
27 | 
28 | 
29 | 
30 | // Solution of the Problem : 
31 | 
32 | #include <cmath>
33 | #include <cstdio>
34 | #include <vector>
35 | #include <iostream>
36 | #include <algorithm>
37 | using namespace std;
38 | 
39 | int main() {
40 |     /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
41 |     
42 |     // Taking Input of the length of the Vector Array
43 |     int length;
44 |     cin >> length;
45 |     
46 |     // Taking the Integer array vector
47 |     vector<int>arr;
48 |     
49 |     // Taking input of the Array
50 |     for(int i=0;i<length;i++)
51 |     {
52 |     // In this For loop initialize an integer x and take the input n times and push back     that integer to the vector
53 |         int x;
54 |         cin >> x;
55 |         arr.push_back(x);
56 |     }
57 |     
58 |     // Now sort the vector using sort() function
59 |     sort(arr.begin(),arr.end());
60 |     
61 |     // Now give the output of the sorted array
62 |      for(int i=0;i<length;i++)
63 |      {
64 |         cout << arr[i] << " ";
65 |      }
66 |      
67 |      
68 |     return 0;
69 | }
70 | 


--------------------------------------------------------------------------------
/C++/05. Inheritance/Accessing Inherited Functions.cpp:
--------------------------------------------------------------------------------
  1 | /*
  2 | Problem Link : https://www.hackerrank.com/challenges/accessing-inherited-functions/problem
  3 | Problem : Accessing Inherited Functions
  4 | Category: C++ Inheritance
  5 | Difficulty: Medium
  6 | Max Score: 30
  7 | */
  8 | #include <iostream>
  9 | using namespace std;
 10 | class A
 11 | {
 12 | public:
 13 |     A()
 14 |     {
 15 |         callA = 0;
 16 |     }
 17 | 
 18 | private:
 19 |     int callA;
 20 |     void inc()
 21 |     {
 22 |         callA++;
 23 |     }
 24 | 
 25 | protected:
 26 |     void func(int &a)
 27 |     {
 28 |         a = a * 2;
 29 |         inc();
 30 |     }
 31 | 
 32 | public:
 33 |     int getA()
 34 |     {
 35 |         return callA;
 36 |     }
 37 | };
 38 | class B
 39 | {
 40 | public:
 41 |     B()
 42 |     {
 43 |         callB = 0;
 44 |     }
 45 | 
 46 | private:
 47 |     int callB;
 48 |     void inc()
 49 |     {
 50 |         callB++;
 51 |     }
 52 | 
 53 | protected:
 54 |     void func(int &a)
 55 |     {
 56 |         a = a * 3;
 57 |         inc();
 58 |     }
 59 | 
 60 | public:
 61 |     int getB()
 62 |     {
 63 |         return callB;
 64 |     }
 65 | };
 66 | class C
 67 | {
 68 | public:
 69 |     C()
 70 |     {
 71 |         callC = 0;
 72 |     }
 73 | 
 74 | private:
 75 |     int callC;
 76 |     void inc()
 77 |     {
 78 |         callC++;
 79 |     }
 80 | 
 81 | protected:
 82 |     void func(int &a)
 83 |     {
 84 |         a = a * 5;
 85 |         inc();
 86 |     }
 87 | 
 88 | public:
 89 |     int getC()
 90 |     {
 91 |         return callC;
 92 |     }
 93 | };
 94 | /* Accessing Inherited Functions in C++ - Hacker Rank Solution START */
 95 | class D : public A, B, C
 96 | {
 97 |     int val;
 98 | 
 99 | public:
100 |     // Initially val is 1
101 |     D()
102 |     {
103 |         val = 1;
104 |     }
105 |     // Implement this function
106 |     void update_val(int new_val)
107 |     {
108 |         int a = new_val;
109 |         while (new_val != 0)
110 |         {
111 |             if (val == a)
112 |                 break;
113 |             if (new_val % 2 == 0)
114 |             {
115 |                 A::func(val);
116 |                 new_val /= 2;
117 |             }
118 |             else if (new_val % 3 == 0)
119 |             {
120 |                 B::func(val);
121 |                 new_val /= 3;
122 |             }
123 |             else if (new_val % 5 == 0)
124 |             {
125 |                 C::func(val);
126 |                 new_val /= 5;
127 |             }
128 |         }
129 |     }
130 |     // For Checking Purpose
131 |     void check(int); // Do not delete this line.
132 | };
133 | /* Accessing Inherited Functions in C++ - Hacker Rank Solution END */
134 | void D::check(int new_val)
135 | {
136 |     update_val(new_val);
137 |     cout << "Value = " << val << endl
138 |          << "A's func called " << getA() << " times " << endl
139 |          << "B's func called " << getB() << " times" << endl
140 |          << "C's func called " << getC() << " times" << endl;
141 | }
142 | int main()
143 | {
144 |     D d;
145 |     int new_val;
146 |     cin >> new_val;
147 |     d.check(new_val);
148 | }


--------------------------------------------------------------------------------
/C++/05. Inheritance/Multi_Level_Inheritance.cpp:
--------------------------------------------------------------------------------
 1 | /*
 2 | Problem Link : https://www.hackerrank.com/challenges/multi-level-inheritance-cpp/problem?isFullScreen=true
 3 | Problem : Multi_Level_Inheritance
 4 | Category: Inheritance
 5 | Difficulty: Easy
 6 | Max Score: 25
 7 | */
 8 | 
 9 | #include <cmath>
10 | #include <cstdio>
11 | #include <vector>
12 | #include <iostream>
13 | #include <algorithm>
14 | using namespace std;
15 | 
16 | class Triangle{
17 | 	public:
18 | 		void triangle(){
19 | 			cout<<"I am a triangle\n";
20 | 		}
21 | };
22 | 
23 | class Isosceles : public Triangle{
24 |   	public:
25 |   		void isosceles(){
26 |     		cout<<"I am an isosceles triangle\n";
27 |   		}
28 | };
29 | 
30 | //Write your code here.
31 | class Equilateral:public Isosceles{
32 |     public:
33 |         void equilateral(){
34 |             cout<<"I am an equilateral triangle"<<"\n";
35 |         }
36 | };
37 | int main(){
38 |   
39 |     Equilateral eqr;
40 |     eqr.equilateral();
41 |     eqr.isosceles();
42 |     eqr.triangle();
43 |     return 0;
44 | }
45 | 


--------------------------------------------------------------------------------
/C++/05. Inheritance/Rectangle Area.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link :https://www.hackerrank.com/challenges/rectangle-area/problem
 2 | //Difficulty : Easy
 3 | //Max Score:25
 4 | 
 5 | 
 6 | #include <cmath>
 7 | #include <cstdio>
 8 | #include <vector>
 9 | #include <iostream>
10 | #include <algorithm>
11 | using namespace std;
12 | 
13 | 
14 | int main() {
15 |     int h,w;
16 |     //taking input 
17 |     cin>>h>>w;
18 |     //print height and width
19 |     cout<<h<<" "<<w<<endl;
20 |     // print the calculated area 
21 |     cout<<h*w ;
22 |     return 0;
23 | }
24 | 


--------------------------------------------------------------------------------
/C++/06. Debugging/CPP Exception Handling.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/cpp-exception-handling/problem?isFullScreen=true
 2 | // Problem Name : CPP Exception Handling
 3 | // Language : C++
 4 | // Subdomain : Debugging
 5 | // Max Score : 20
 6 | // Difficulty : Medium
 7 | 
 8 | #include <iostream>
 9 | #include <stdexcept>
10 | 
11 | using namespace std;
12 | 
13 | int largest_proper_divisor(int n)
14 | {
15 |     if (n == 0)
16 |     {
17 |         throw invalid_argument("largest proper divisor is not defined for n=0");
18 |     }
19 |     if (n == 1)
20 |     {
21 |         throw invalid_argument("largest proper divisor is not defined for n=1");
22 |     }
23 |     for (int i = n / 2; i >= 1; --i)
24 |     {
25 |         if (n % i == 0)
26 |         {
27 |             return i;
28 |         }
29 |     }
30 |     return -1; // will never happen
31 | }
32 | 
33 | void process_input(int n)
34 | {
35 |     try
36 |     {
37 |         int d = largest_proper_divisor(n);
38 |         cout << "result=" << d << endl;
39 |     }
40 |     catch (exception &e)
41 |     {
42 |         cout << e.what() << endl;
43 |     }
44 |     cout << "returning control flow to caller" << endl;
45 | }
46 | 
47 | int main()
48 | {
49 |     int n;
50 |     cin >> n;
51 |     process_input(n);
52 |     return 0;
53 | }


--------------------------------------------------------------------------------
/C++/06. Debugging/Overloading Ostream Operator.cpp:
--------------------------------------------------------------------------------
 1 | // Problem link: https://www.hackerrank.com/challenges/overloading-ostream-operator/problem?isFullScreen=true
 2 | // Problem: Overloading Ostream Operator
 3 | // Language: C++
 4 | // Subdomain: Debugging
 5 | // Score: 20
 6 | // Difficulty: Medium
 7 | 
 8 | #include <iostream>
 9 | 
10 | using namespace std;
11 | 
12 | class Person
13 | {
14 | public:
15 |     Person(const string &first_name, const string &last_name) : first_name_(first_name), last_name_(last_name) {}
16 |     const string &get_first_name() const
17 |     {
18 |         return first_name_;
19 |     }
20 |     const string &get_last_name() const
21 |     {
22 |         return last_name_;
23 |     }
24 | 
25 | private:
26 |     string first_name_;
27 |     string last_name_;
28 | };
29 | ostream &operator<<(ostream &os, const Person &rhs)
30 | {
31 |     os << "first_name=" << rhs.get_first_name() << ",last_name=" << rhs.get_last_name();
32 |     return os;
33 | }
34 | 


--------------------------------------------------------------------------------
/C++/07. Other Concepts/Operator Overloading.cpp:
--------------------------------------------------------------------------------
 1 | // Problem: Operator Overloading
 2 | // Problem Link: https://www.hackerrank.com/challenges/operator-overloading/problem?isFullScreen=true
 3 | // Language: C++
 4 | // Difficulty: Medium
 5 | // Max Score: 25
 6 | 
 7 | #include <cmath>
 8 | #include <cstdio>
 9 | #include <vector>
10 | #include <iostream>
11 | #include <algorithm>
12 | using namespace std;
13 | 
14 | class Matrix
15 | {
16 | public:
17 |     vector<vector<int>> a;
18 | 
19 |     Matrix(){};
20 | 
21 |     Matrix operator+(const Matrix &y)
22 |     {
23 |         for (int i = 0; i < y.a.size(); i++)
24 |         {
25 |             for (int j = 0; j < y.a[0].size(); j++)
26 |             {
27 |                 this->a[i][j] = this->a[i][j] + y.a[i][j];
28 |             }
29 |         }
30 | 
31 |         return *this;
32 |     }
33 | };
34 | 
35 | int main()
36 | {
37 |     int cases, k;
38 |     cin >> cases;
39 |     for (k = 0; k < cases; k++)
40 |     {
41 |         Matrix x;
42 |         Matrix y;
43 |         Matrix result;
44 |         int n, m, i, j;
45 |         cin >> n >> m;
46 |         for (i = 0; i < n; i++)
47 |         {
48 |             vector<int> b;
49 |             int num;
50 |             for (j = 0; j < m; j++)
51 |             {
52 |                 cin >> num;
53 |                 b.push_back(num);
54 |             }
55 |             x.a.push_back(b);
56 |         }
57 |         for (i = 0; i < n; i++)
58 |         {
59 |             vector<int> b;
60 |             int num;
61 |             for (j = 0; j < m; j++)
62 |             {
63 |                 cin >> num;
64 |                 b.push_back(num);
65 |             }
66 |             y.a.push_back(b);
67 |         }
68 |         result = x + y;
69 |         for (i = 0; i < n; i++)
70 |         {
71 |             for (j = 0; j < m; j++)
72 |             {
73 |                 cout << result.a[i][j] << " ";
74 |             }
75 |             cout << endl;
76 |         }
77 |     }
78 |     return 0;
79 | }
80 | 


--------------------------------------------------------------------------------
/C++/STL/vector-sort.cpp:
--------------------------------------------------------------------------------
 1 | 
 2 | #include <cmath>
 3 | #include <cstdio>
 4 | #include <vector>
 5 | #include <iostream>
 6 | #include <algorithm>
 7 | using namespace std;
 8 | 
 9 | int main() {
10 |     /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
11 |     
12 |     // Taking Input of the length of the Vector Array
13 |     int length;
14 |     cin >> length;
15 |     
16 |     // Taking the Integer array vector
17 |     vector<int>arr;
18 |     
19 |     // Taking input of the Array
20 |     for(int i=0;i<length;i++)
21 |     {
22 |     // In this For loop initialize an integer x and take the input n times and push back     that integer to the vector
23 |         int x;
24 |         cin >> x;
25 |         arr.push_back(x);
26 |     }
27 |     
28 |     // Now sort the vector using sort() function
29 |     sort(arr.begin(),arr.end());
30 |     
31 |     // Now give the output of the sorted array
32 |      for(int i=0;i<length;i++)
33 |      {
34 |         cout << arr[i] << " ";
35 |      }
36 |      
37 |      
38 |     return 0;
39 | }
40 | 


--------------------------------------------------------------------------------
/CODE_OF_CONDUCT.md:
--------------------------------------------------------------------------------
  1 | # Contributor Covenant Code of Conduct
  2 | 
  3 | ## Our Pledge
  4 | 
  5 | We as members, contributors, and leaders pledge to make participation in our
  6 | community a harassment-free experience for everyone, regardless of age, body
  7 | size, visible or invisible disability, ethnicity, sex characteristics, gender
  8 | identity and expression, level of experience, education, socio-economic status,
  9 | nationality, personal appearance, race, religion, or sexual identity
 10 | and orientation.
 11 | 
 12 | We pledge to act and interact in ways that contribute to an open, welcoming,
 13 | diverse, inclusive, and healthy community.
 14 | 
 15 | ## Our Standards
 16 | 
 17 | Examples of behavior that contributes to a positive environment for our
 18 | community include:
 19 | 
 20 | * Demonstrating empathy and kindness toward other people
 21 | * Being respectful of differing opinions, viewpoints, and experiences
 22 | * Giving and gracefully accepting constructive feedback
 23 | * Accepting responsibility and apologizing to those affected by our mistakes,
 24 |   and learning from the experience
 25 | * Focusing on what is best not just for us as individuals, but for the
 26 |   overall community
 27 | 
 28 | Examples of unacceptable behavior include:
 29 | 
 30 | * The use of sexualized language or imagery, and sexual attention or
 31 |   advances of any kind
 32 | * Trolling, insulting or derogatory comments, and personal or political attacks
 33 | * Public or private harassment
 34 | * Publishing others' private information, such as a physical or email
 35 |   address, without their explicit permission
 36 | * Other conduct which could reasonably be considered inappropriate in a
 37 |   professional setting
 38 | 
 39 | ## Enforcement Responsibilities
 40 | 
 41 | Community leaders are responsible for clarifying and enforcing our standards of
 42 | acceptable behavior and will take appropriate and fair corrective action in
 43 | response to any behavior that they deem inappropriate, threatening, offensive,
 44 | or harmful.
 45 | 
 46 | Community leaders have the right and responsibility to remove, edit, or reject
 47 | comments, commits, code, wiki edits, issues, and other contributions that are
 48 | not aligned to this Code of Conduct, and will communicate reasons for moderation
 49 | decisions when appropriate.
 50 | 
 51 | ## Scope
 52 | 
 53 | This Code of Conduct applies within all community spaces, and also applies when
 54 | an individual is officially representing the community in public spaces.
 55 | Examples of representing our community include using an official e-mail address,
 56 | posting via an official social media account, or acting as an appointed
 57 | representative at an online or offline event.
 58 | 
 59 | ## Enforcement
 60 | 
 61 | Instances of abusive, harassing, or otherwise unacceptable behavior may be
 62 | reported to the community leaders responsible for enforcement at
 63 | riddhi0bhagat@gmail.com.
 64 | All complaints will be reviewed and investigated promptly and fairly.
 65 | 
 66 | All community leaders are obligated to respect the privacy and security of the
 67 | reporter of any incident.
 68 | 
 69 | ## Enforcement Guidelines
 70 | 
 71 | Community leaders will follow these Community Impact Guidelines in determining
 72 | the consequences for any action they deem in violation of this Code of Conduct:
 73 | 
 74 | ### 1. Correction
 75 | 
 76 | **Community Impact**: Use of inappropriate language or other behavior deemed
 77 | unprofessional or unwelcome in the community.
 78 | 
 79 | **Consequence**: A private, written warning from community leaders, providing
 80 | clarity around the nature of the violation and an explanation of why the
 81 | behavior was inappropriate. A public apology may be requested.
 82 | 
 83 | ### 2. Warning
 84 | 
 85 | **Community Impact**: A violation through a single incident or series
 86 | of actions.
 87 | 
 88 | **Consequence**: A warning with consequences for continued behavior. No
 89 | interaction with the people involved, including unsolicited interaction with
 90 | those enforcing the Code of Conduct, for a specified period of time. This
 91 | includes avoiding interactions in community spaces as well as external channels
 92 | like social media. Violating these terms may lead to a temporary or
 93 | permanent ban.
 94 | 
 95 | ### 3. Temporary Ban
 96 | 
 97 | **Community Impact**: A serious violation of community standards, including
 98 | sustained inappropriate behavior.
 99 | 
100 | **Consequence**: A temporary ban from any sort of interaction or public
101 | communication with the community for a specified period of time. No public or
102 | private interaction with the people involved, including unsolicited interaction
103 | with those enforcing the Code of Conduct, is allowed during this period.
104 | Violating these terms may lead to a permanent ban.
105 | 
106 | ### 4. Permanent Ban
107 | 
108 | **Community Impact**: Demonstrating a pattern of violation of community
109 | standards, including sustained inappropriate behavior,  harassment of an
110 | individual, or aggression toward or disparagement of classes of individuals.
111 | 
112 | **Consequence**: A permanent ban from any sort of public interaction within
113 | the community.
114 | 
115 | ## Attribution
116 | 
117 | This Code of Conduct is adapted from the [Contributor Covenant][homepage],
118 | version 2.0, available at
119 | https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
120 | 
121 | Community Impact Guidelines were inspired by [Mozilla's code of conduct
122 | enforcement ladder](https://github.com/mozilla/diversity).
123 | 
124 | [homepage]: https://www.contributor-covenant.org
125 | 
126 | For answers to common questions about this code of conduct, see the FAQ at
127 | https://www.contributor-covenant.org/faq. Translations are available at
128 | https://www.contributor-covenant.org/translations.
129 | 


--------------------------------------------------------------------------------
/CONTRIBUTING.md:
--------------------------------------------------------------------------------
  1 | # 🎇Contributing Guidelines
  2 | 
  3 | ---
  4 | 
  5 | First of all thanks for taking time out to contribute :smiley: :partying_face:
  6 | 
  7 | This documentation contains a set of guidelines to help you during the contribution process.
  8 | 
  9 | ## 💻Before Contributing
 10 | 
 11 | Welcome to [Riddhi9570/HackerrankPracticeProblems](https://github.com/Riddhi9570/HackerrankPracticeProblems). Before sending your pull requests, make sure that you **read the whole
 12 | guidelines**. If you have any doubt about the contributing guide, please feel free to reach out.
 13 | 
 14 | ## 🙌Contribution
 15 | 
 16 | Your contributions can be adding a solution to a **new practice problem** of the **existing domain (SQL)** or you can come up with the solution of **any other domain (For example, C++, Java, Python, etc.)**. Please read this section if you are contributing your work.
 17 | 
 18 | ### 🔖Steps to Contribute
 19 | 
 20 | Following are the steps to guide you:
 21 | 
 22 | * Step 1: Star and Fork the repo Go to your Git terminal and clone it on your machine.
 23 | * Step 2: Add an upstream link to the main branch in your cloned repo
 24 |     ```
 25 |     git remote add upstream https://github.com/Riddhi9570/HackerrankPracticeProblems.git
 26 |     ```
 27 | * Step 3: Keep your cloned repo up to date by pulling from upstream (this will also avoid any merge conflicts while committing new changes)
 28 |     ```
 29 |     git pull upstream main
 30 |     ```
 31 | * Step 4: Create your feature branch (This is a necessary step, so don't skip it)
 32 |     ```
 33 |     git checkout -b <feature-name>
 34 |     ```
 35 | * Step 5: Commit all the changes (Write commit message as "Small Message")
 36 |     ```
 37 |     git commit -m "Write a meaningful but small commit message"
 38 |     ```
 39 | * Step 6: Push the changes for review
 40 |     ```
 41 |     git push origin <branch-name>
 42 |     ```
 43 | * Step 7: Create a PR on Github. (Don't just hit the create a pull request button, you must write a PR message to clarify why and what are you contributing)
 44 | 
 45 | ### 🔑Guidelines
 46 | 
 47 | Here are some set of guidelines to follow while contributing to `HackerrankPracticeProblems` :
 48 | 
 49 | 1. Welcome to this repository, if you are here as an open-source program participant/contributor.
 50 | 2. Participants/contributors have to **comment** on issues they would like to work on, and mentors or the PA will assign you.
 51 | 3. Issues will be assigned on a **first-come, first-serve basis.**
 52 | 4. Participants/contributors can also **open their issues**, but it needs to be verified and labelled by a mentor or PA. We respect all your contributions, whether 
 53 | it is an Issue or a Pull Request.
 54 | 5. When you raise an issue, make sure you get it assigned to you before you start working on that project.
 55 | 6. Each participant/contributor will be **assigned 1 issue (max)** at a time to work.
 56 | 7. Don't create issues that are **already listed**.
 57 | 8. Please don't pick up an issue already assigned to someone else. Work on the issues after it gets **assigned to you**.
 58 | 9. Create your file in an appropriate folder with appropriate name and extension.
 59 | 10. When you are adding solution for a hackerrank problem, add these comments at the top your solution:
 60 |   - `-- # Problem Link :` < problem link >
 61 |     <br> For example, <br> -- # Problem Link: https://www.hackerrank.com/challenges/multi-level-inheritance-cpp/problem
 62 |   - `-- # Problem :` < problem name >
 63 |     <br> For example, <br> -- # Problem : Multi Level Inheritance
 64 |   - `-- # Language :` < programming language >
 65 |     <br> For example, <br> -- # Language : C++
 66 |   - `-- # Subdomain :` < subdomain of problem in hackerrank >
 67 |     <br> For example, <br> -- # Subdomain : Inheritance
 68 |   - `-- # Max Score :` < Maximum score for that problem >
 69 |     <br> For example, <br> -- # Max Score : 25 
 70 |   - `-- # Difficulty :` < Easy/Medium/Hard >
 71 |     <br> For example, <br> -- # Difficulty : Easy
 72 | 11. It would be appreciated if you add approach and notes to your solution (especially for difficult problems)- [Example 1](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/10.%20Weather%20Observation%20Station%205.sql), [Example 2](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/17.%20Weather%20Observation%20Station%2020.sql).
 73 | 12. Create a pull request and also give your hackerrank submission link in the description so that it can be easily reviewed and merged.
 74 | 13. Pull requests will be merged after being **reviewed** by a mentor or PA.
 75 | <!--14. After your PR has been merged, please update [README.md](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/README.md) as follows:
 76 |   - Find the appropriate position in Readme.md for adding your problem details. 
 77 |   - Syntax :
 78 |     ` | S.No. | [Problem Name](problem link) | [Solution](github link to the solution) | Score | Difficulty (Easy/Medium/Hard) |`
 79 |     <br> For example, <br> | 03. | [Select All](https://www.hackerrank.com/challenges/select-all-sql/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/03.%20Select%20All.sql) | 10 | Easy |
 80 |   - If you have added a new folder (for new language or new subdomain), then follow the pattern given in README.md and update it accordingly. -->
 81 | 14. We all are here to learn. You are allowed to make mistakes. That's how you learn, right!.
 82 | 
 83 | ### 🧲Pull Requests Review Criteria
 84 | 
 85 | <!-- Please fill the **[PR Template](PrTemplateLink)** properly while making a Pull Request. -->
 86 | - You must add your file into the respective **folder**.
 87 | - Your work must be original, written by you not copied from other resources.
 88 | - You must comment on your code wherever necessary.
 89 | - Follow the proper [style guides](https://google.github.io/styleguide/) for your work.
 90 | - For any queries or discussions, please feel free to drop a message.
 91 | 
 92 | ## 📖Resources
 93 | 
 94 | 1. Markdown: Markdown is a lightweight markup language like HTML, with plain text formatting syntax. 
 95 |   * [Markdown Cheat-Sheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet)
 96 | 
 97 | 2. Git: Git is a distributed version control system for tracking changes in source code during software development. It is designed for coordinating work among programmers, but it can be used to track changes in any set of files.
 98 |   * [Videos to get started](https://www.youtube.com/watch?v=xAAmje1H9YM&list=PLeo1K3hjS3usJuxZZUBdjAcilgfQHkRzW)
 99 |   * [Cheat Sheet](https://www.atlassian.com/git/tutorials/atlassian-git-cheatsheet)
100 | 
101 | ## 🤔Need more help?
102 | 
103 | You can refer to the following articles on the basics of Git and Github and also contact me, in case you are stuck:
104 | - [Forking a Repo](https://help.github.com/en/github/getting-started-with-github/fork-a-repo)
105 | - [Cloning a Repo](https://help.github.com/en/desktop/contributing-to-projects/creating-an-issue-or-pull-request)
106 | - [How to create a Pull Request](https://opensource.com/article/19/7/create-pull-request-github)
107 | - [Getting started with Git and GitHub](https://towardsdatascience.com/getting-started-with-git-and-github-6fcd0f2d4ac6)
108 | - [Learn GitHub from Scratch](https://lab.github.com/githubtraining/introduction-to-github)
109 | 
110 | ## 😇Tip from me
111 | 
112 | It always takes time to understand and learn. So, do not worry at all. I know you can do this**!💪
113 | 
114 | ### [![Typing SVG](https://readme-typing-svg.herokuapp.com/?lines=Thanks+for+contributing!;&size=30)](https://git.io/typing-svg)
115 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Currency Formatter.java:
--------------------------------------------------------------------------------
 1 | // Problem - https://www.hackerrank.com/challenges/java-currency-formatter/problem?isFullScreen=true
 2 | // Score - 15
 3 | // Difficulty - Easy
 4 | 
 5 | import java.util.*;
 6 | import java.text.*;
 7 | 
 8 | public class Currencyformatter {
 9 |     
10 |     public static void main(String[] args) {
11 |         Scanner scanner = new Scanner(System.in);
12 |         //Input
13 |         System.out.print("Enter amount: ");
14 |         double payment = scanner.nextDouble();
15 |         scanner.close();
16 |         
17 |         Locale indiaLocale = new Locale("en", "IN");
18 | 
19 |         /* Create NumberFormats using Locales */
20 |         NumberFormat us     = NumberFormat.getCurrencyInstance(Locale.US);
21 |         NumberFormat india  = NumberFormat.getCurrencyInstance(indiaLocale);
22 |         NumberFormat china  = NumberFormat.getCurrencyInstance(Locale.CHINA);
23 |         NumberFormat france = NumberFormat.getCurrencyInstance(Locale.FRANCE);
24 | 
25 |         /* Print output */        
26 |         System.out.println("US: "     + us.format(payment));
27 |         System.out.println("India: "  + india.format(payment));
28 |         System.out.println("China: "  + china.format(payment));
29 |         System.out.println("France: " + france.format(payment));
30 |     
31 |     }
32 | }


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Datatypes.java:
--------------------------------------------------------------------------------
 1 | // Problem: https://www.hackerrank.com/challenges/java-datatypes/problem?isFullScreen=true
 2 | // Score: 10
 3 | // Difficulty: Easy
 4 | 
 5 | 
 6 | import java.util.*;
 7 | import java.io.*;
 8 | 
 9 | class Solution{
10 |     public static void main(String []argh)
11 |     {
12 |         Scanner sc = new Scanner(System.in);
13 |         int t=sc.nextInt();
14 |         for(int i=0;i<t;i++) {
15 |             try {
16 |                 long x=sc.nextLong();
17 |                 System.out.println(x+" can be fitted in:");
18 |                 if(x>=-128 && x<=127)System.out.println("* byte");
19 |                 if(x>=-32768 && x<32768)System.out.println("* short");
20 |                 if(x>=-Math.pow(2,31) && x<=Math.pow(2,31)-1)System.out.println("* int");
21 |                 if(x>=-Math.pow(2,63) && x<=Math.pow(2,63)-1)System.out.println("* long");
22 |             }
23 |             catch(Exception e) {
24 |                 System.out.println(sc.next()+" can't be fitted anywhere.");
25 |             }
26 |         }
27 |     }
28 | }
29 | 
30 | 
31 | 
32 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Date and Time.java:
--------------------------------------------------------------------------------
 1 | // Problem - https://www.hackerrank.com/challenges/java-date-and-time/problem?isFullScreen=true
 2 | // Score - 15
 3 | // Difficulty - Easy
 4 | 
 5 | import java.io.*;
 6 | import java.math.*;
 7 | import java.security.*;
 8 | import java.text.*;
 9 | import java.util.*;
10 | import java.util.concurrent.*;
11 | import java.util.function.*;
12 | import java.util.regex.*;
13 | import java.util.stream.*;
14 | import static java.util.stream.Collectors.joining;
15 | import static java.util.stream.Collectors.toList;
16 | import java.util.Calendar;
17 | class Result {
18 | 
19 |     /*
20 |      * Complete the 'findDay' function below.
21 |      *
22 |      * The function is expected to return a STRING.
23 |      * The function accepts following parameters:
24 |      *  1. INTEGER month
25 |      *  2. INTEGER day
26 |      *  3. INTEGER year   import java.util.Calendar;   import java.util.Calendar;
27 |      */
28 | 
29 |     public static String findDay(int month, int day, int year) {
30 |         Calendar cal=Calendar.getInstance();
31 |         String dd[]={"SUNDAY","MONDAY","TUESDAY","WEDNESDAY","THURSDAY","FRIDAY","SATURDAY"};
32 |         cal.set(year,month-1,day);
33 |         int n=cal.get(Calendar.DAY_OF_WEEK);
34 |         return dd[n-1];
35 |     }
36 | 
37 | }
38 | 
39 | public class Solution {
40 |     public static void main(String[] args) throws IOException {
41 |         BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
42 |         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
43 | 
44 |         String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");
45 | 
46 |         int month = Integer.parseInt(firstMultipleInput[0]);
47 | 
48 |         int day = Integer.parseInt(firstMultipleInput[1]);
49 | 
50 |         int year = Integer.parseInt(firstMultipleInput[2]);
51 | 
52 |         String res = Result.findDay(month, day, year);
53 | 
54 |         bufferedWriter.write(res);
55 |         bufferedWriter.newLine();
56 | 
57 |         bufferedReader.close();
58 |         bufferedWriter.close();
59 |     }
60 | }
61 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java If-Else.java:
--------------------------------------------------------------------------------
 1 | // problem link -> https://www.hackerrank.com/challenges/java-if-else/problem
 2 | // Score: 10
 3 | // Difficulty : Easy
 4 | 
 5 | 
 6 | 
 7 | import java.util.Scanner;
 8 | public class if_else {
 9 |     public static void main(String[] args) {
10 |         Scanner in = new Scanner(System.in);
11 |         System.out.println("Enter the number between 1-100");
12 | 
13 |         int n = in.nextInt();
14 |         String ans = "";
15 | 
16 |         if(n%2!=0){             // if the value of n is odd ans = weird
17 |             ans = "Weird";
18 |         } else if (n>=2 && n <= 5){     // if the value of n is between 2&5 and is even ans = not weird
19 |             ans = "Not Weird";
20 |         } else if (n>=6 && n <= 20) {   // if the value of n i between 6&20 and is even ans = weird
21 |             ans = "Weird";
22 |         } else {                        // if the valur of n>20 and is even ans = not weird
23 |             ans = "Not Weird";
24 |         }
25 |         System.out.println(ans);
26 |     }
27 | }
28 | 
29 | // Method 2 : by calling a function
30 | 
31 | import java.util.Scanner;
32 | public class if_else {
33 |     public static void main(String[] args) {
34 |         Scanner in = new Scanner(System.in);
35 |         System.out.println("Enter the value of between 1-100");
36 |         int n = in.nextInt();           // taking input from the user
37 |         System.out.println(check(n));
38 |     }
39 |     static String check(int n) {
40 |         if(n%2!=0) {                       // if the value of n is odd return weird
41 |             return "weird";
42 |         } else if ( n>=2 && n<=5) {        // if the value of n is between 2&5 and is even return not weird
43 |             return "not weird";
44 |         } else if ( n>=6 && n<=20) {       // if the value of n i between 6&20 and is even return weird
45 |             return "weird";
46 |         } else if (n>20) {
47 |             return "not weird";            // if the valur of n>20 and is even return not weird
48 |         }
49 |         return null;
50 |     }
51 | }


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Int to String.java:
--------------------------------------------------------------------------------
 1 | 
 2 | //-- # Problem : https://www.hackerrank.com/challenges/java-int-to-string/problem?isFullScreen=true
 3 | 
 4 | //-- # Score : 10
 5 | 
 6 | //-- # Difficulty : Easy
 7 | 
 8 | import java.util.*;
 9 | import java.security.*;
10 | public class Solution {
11 |  public static void main(String[] args) {
12 | 
13 |   DoNotTerminate.forbidExit();
14 | 
15 |   try {
16 |    Scanner in = new Scanner(System.in);
17 |    int n = in .nextInt();
18 |    in.close();
19 |    //this line Converts Int to String
20 |     String s=Integer.toString(n);   
21 |     //it checks whether it was converted or not
22 |    if (n == Integer.parseInt(s)) {
23 |     System.out.println("Good job");
24 |    } else {
25 |     System.out.println("Wrong answer.");
26 |    }
27 |   } catch (DoNotTerminate.ExitTrappedException e) {
28 |    System.out.println("Unsuccessful Termination!!");
29 |   }
30 |  }
31 | }
32 | 
33 | //The following class will prevent you from terminating the code using exit(0)!
34 | class DoNotTerminate {
35 | 
36 |  public static class ExitTrappedException extends SecurityException {
37 | 
38 |   private static final long serialVersionUID = 1;
39 |  }
40 | 
41 |  public static void forbidExit() {
42 |   final SecurityManager securityManager = new SecurityManager() {
43 |    @Override
44 |    public void checkPermission(Permission permission) {
45 |     if (permission.getName().contains("exitVM")) {
46 |      throw new ExitTrappedException();
47 |     }
48 |    }
49 |   };
50 |   System.setSecurityManager(securityManager);
51 |  }
52 | }
53 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Loops II.java:
--------------------------------------------------------------------------------
 1 | package Java;
 2 | 
 3 | import java.util.Scanner;
 4 | 
 5 | //-- # Problem : https://www.hackerrank.com/challenges/java-loops/problem?isFullScreen=true
 6 | 
 7 | //-- # Score : 10
 8 | 
 9 | //-- # Difficulty : Easy
10 | 
11 | class Solution{
12 |     public static void main(String []argh){
13 |         Scanner in = new Scanner(System.in);
14 |         int t=in.nextInt();
15 |         for(int i=0;i<t;i++){
16 |             int a = in.nextInt();
17 |             int b = in.nextInt();
18 |             int n = in.nextInt();
19 |             for(int j = 0;j<n;j++)
20 |             {
21 |                 a = a + (int)Math.pow(2,j)*b;
22 |                 System.out.print(a + " ");
23 |             }            
24 |             System.out.println("");
25 |         }
26 |         in.close();
27 |     }
28 | }
29 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Static initializer block.java:
--------------------------------------------------------------------------------
 1 | //#Problem Link - https://www.hackerrank.com/challenges/java-static-initializer-block/problem?isFullScreen=true
 2 | //#Problem - Java Static initializer block
 3 | //#Language - JAVA
 4 | //#Subdomain - Introduction
 5 | //#Max-Score - 10
 6 | //#Difficulty - Easy
 7 | import java.util.*;
 8 | 
 9 | public class Solution {
10 | // Creation of individual static variables 
11 | static Scanner in=new Scanner(System.in);
12 | static int B=in.nextInt();
13 | static int H=in.nextInt();
14 | static boolean flag=true;
15 | // Adding conditionals in static block
16 | static{
17 |     try{
18 |         if(B<=0 || H<=0)
19 |         {
20 |             flag=false;
21 |             // Creating exception and executing it if condition is satisfied
22 |             throw new Exception("Breadth and height must be positive");
23 |         }
24 |     }
25 |         catch(Exception e){
26 |             System.out.println(e);
27 |         }
28 | }
29 | 
30 | public static void main(String[] args){
31 | 		if(flag){
32 | 			int area=B*H;
33 | 			System.out.print(area);
34 | 		}
35 | 		
36 | 	}//end of main
37 | 
38 | }//end of class
39 | 
40 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Stdin and Stdout I.java:
--------------------------------------------------------------------------------
 1 | # problem :java Stdin and Stdout I
 2 | #Score : 5.0
 3 | # Difficulty- Easy
 4 | 
 5 | import java.util.*;
 6 | 
 7 | public class Solution {
 8 | 
 9 |     public static void main(String[] args) {
10 |         Scanner scan = new Scanner(System.in);
11 |         int a = scan.nextInt();
12 |         int b = scan.nextInt();
13 |         int c = scan.nextInt();
14 |         
15 | 
16 |         System.out.println(a);
17 |         System.out.println(b);
18 |         System.out.println(c);
19 |         
20 |     }
21 | }
22 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Java Stdin and Stdout II.java:
--------------------------------------------------------------------------------
 1 | // Problem - https://www.hackerrank.com/challenges/java-stdin-stdout/problem
 2 | // Score - 10
 3 | // Difficulty - Easy
 4 | 
 5 | 
 6 | import java.util.Scanner;
 7 | 
 8 | public class Solution {
 9 | 
10 |     public static void main(String[] args) {
11 |         Scanner scan = new Scanner(System.in);
12 |         int i = scan.nextInt();
13 |         double d = scan.nextDouble();
14 |         scan.nextLine();
15 |         String s = scan.nextLine();
16 | 
17 |         System.out.println("String: " + s);
18 |         System.out.println("Double: " + d);
19 |         System.out.println("Int: " + i);
20 |     }
21 | }
22 | 


--------------------------------------------------------------------------------
/Java/01. Introduction/Welcome To Java.java:
--------------------------------------------------------------------------------
 1 | // Problem - https://www.hackerrank.com/challenges/welcome-to-java/problem?isFullScreen=true
 2 | // Score - 3
 3 | // Difficulty - Easy
 4 | 
 5 | 
 6 | public class WelcomeToJava {
 7 |     public static void main(String[] args)
 8 |     {
 9 |         System.out.println("Hello, World.");
10 |         System.out.println("Hello, Java.");
11 |     }
12 | }


--------------------------------------------------------------------------------
/Java/02. Strings/Java Anagrams.java:
--------------------------------------------------------------------------------
 1 | // Problem: https://www.hackerrank.com/challenges/java-anagrams/problem?isFullScreen=true
 2 | // Max Score: 10
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.io.*;
 7 | import java.util.*;
 8 | 
 9 | public class Solution {
10 | 
11 |     public static void main(String[] args) {
12 |         Scanner sc = new Scanner(System.in);
13 |         String s1 = sc.next();
14 |         String s2 = sc.next();
15 |         s1 = s1.toLowerCase();
16 |         s2 = s2.toLowerCase();
17 |         int n = isAnagram(s1, s2);
18 |         if (n == 1)
19 |             System.out.println("Anagrams");
20 |         else
21 |             System.out.println("Not Anagrams");
22 |     }
23 | 
24 |     static int isAnagram(String s1, String s2) {
25 | 
26 |         if (s1.length() == s2.length()) {
27 |             int[] a = new int[256];
28 |             int[] b = new int[256];
29 |             for (int i = 0; i < s1.length(); i++) {
30 |                 ++a[(int) s1.charAt(i)];
31 |                 ++b[(int) s2.charAt(i)];
32 |             }
33 |             for (int i = 0; i < 256; i++) {
34 |                 if (a[i] != b[i])
35 |                     return -1;
36 |             }
37 |             return 1;
38 |         } else
39 |             return -1;
40 |     }
41 | }
42 | 


--------------------------------------------------------------------------------
/Java/02. Strings/Java Substring.java:
--------------------------------------------------------------------------------
 1 | 
 2 | #Problem Link-https://www.hackerrank.com/challenges/java-substring/problem
 3 | #score-5.0
 4 | #Difficulty-Easy
 5 | 
 6 | import java.io.*;
 7 | import java.util.*;
 8 | 
 9 | public class Solution {
10 | 
11 |     public static void main(String[] args) {
12 |         Scanner sc= new Scanner(System.in);
13 |         String s=sc.next();
14 |         int start=sc.nextInt();
15 |         int end= sc.nextInt();
16 |         System.out.println(s.substring(start,end));
17 |     }
18 | }
19 | 


--------------------------------------------------------------------------------
/Java/02. Strings/Java_Int_to_String.java:
--------------------------------------------------------------------------------
 1 | //# Problem Link : https://www.hackerrank.com/challenges/java-int-to-string/problem?isFullScreen=true
 2 | //# Problem : Java Int to String
 3 | //# Language : JAVA
 4 | //# Subdomain : String
 5 | //# Max Score : 10
 6 | //# Difficulty : Easy
 7 | 
 8 | 
 9 | import java.util.*;
10 | import java.security.*;
11 | public class Java_Int_to_String {
12 |  public static void main(String[] args) {
13 | 
14 |   DoNotTerminate.forbidExit();
15 | 
16 |   try {
17 |    Scanner in = new Scanner(System.in);
18 |    int n = in .nextInt();
19 |    in.close();
20 |    //String s=???; Complete this line below
21 | 
22 |    //Write your code here
23 |    String s = Integer.toString(n);
24 | 
25 |    
26 |    if (n == Integer.parseInt(s)) {
27 |     System.out.println("Good job");
28 |    } else {
29 |     System.out.println("Wrong answer.");
30 |    }
31 |   } catch (DoNotTerminate.ExitTrappedException e) {
32 |    System.out.println("Unsuccessful Termination!!");
33 |   }
34 |  }
35 | }
36 | 
37 | //The following class will prevent you from terminating the code using exit(0)!
38 | class DoNotTerminate {
39 | 
40 |  public static class ExitTrappedException extends SecurityException {
41 | 
42 |   private static final long serialVersionUID = 1;
43 |  }
44 | 
45 |  public static void forbidExit() {
46 |   final SecurityManager securityManager = new SecurityManager() {
47 |    @Override
48 |    public void checkPermission(Permission permission) {
49 |     if (permission.getName().contains("exitVM")) {
50 |      throw new ExitTrappedException();
51 |     }
52 |    }
53 |   };
54 |   System.setSecurityManager(securityManager);
55 |  }
56 | }
57 | 


--------------------------------------------------------------------------------
/Java/03. BigNumber/dummy.java:
--------------------------------------------------------------------------------
1 | //This file has to be deleted.


--------------------------------------------------------------------------------
/Java/04. Data Structures/Java 1D Array.java:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/java-1d-array-introduction/problem
 2 | // Max Score: 5
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.util.*;
 7 | 
 8 | public class Solution {
 9 | 
10 |     public static void main(String[] args) {
11 | 
12 |         Scanner scan = new Scanner(System.in);
13 |         int n = scan.nextInt();
14 | 
15 |         // Declaring array a of size n
16 |         int[] a = new int[n];
17 | 
18 |         for (int i = 0; i < n; i++) {
19 |             a[i] = scan.nextInt();
20 |         }
21 | 
22 |         scan.close();
23 | 
24 |         // Prints each sequential element in array a
25 |         for (int i = 0; i < a.length; i++) {
26 |             System.out.println(a[i]);
27 |         }
28 |     }
29 | }


--------------------------------------------------------------------------------
/Java/04. Data Structures/Java Stack.java:
--------------------------------------------------------------------------------
 1 | // Problem : <https://www.hackerrank.com/challenges/java-stack/problem>
 2 | // Language: Java
 3 | // Difficulty: Medium
 4 | // Max Score: 20
 5 | 
 6 | 
 7 | import java.io.*;
 8 | import java.util.*;
 9 | 
10 | public class Solution {
11 | 
12 |     public static void main(String[] args) {
13 |         Scanner sc = new Scanner(System.in);
14 |         while (sc.hasNext()) {
15 |             String input = sc.next();
16 |             if (check(input)){
17 |                 System.out.println("true");
18 |             }
19 |             else {
20 |                 System.out.println("false");
21 |             }
22 |         }
23 |     }
24 |     public static boolean check(String s){
25 |         Stack<Character> stack = new Stack<Character>();
26 |         for (int i = 0; i < s.length();i++){
27 |             if (s.charAt(i) == '(') {
28 |                 stack.push('(');
29 |             }
30 |             else if (s.charAt(i) == '{') {
31 |                 stack.push('{');
32 |             }
33 |             else if (s.charAt(i) == '[') {
34 |                 stack.push('[');
35 |             }
36 |             else if (s.charAt(i) == ')') {
37 |                 if (stack.isEmpty()) {
38 |                     return false;
39 |                 }
40 |                 if (stack.pop() != '(') {
41 |                     return false;
42 |                 }
43 |             }
44 |             else if (s.charAt(i) == '}') {
45 |                 if (stack.isEmpty()) {
46 |                     return false;
47 |                 }
48 |                 if (stack.pop() != '{') {
49 |                     return false;
50 |                 }
51 |             }
52 |             else if (s.charAt(i) == ']') {
53 |                 if (stack.isEmpty()) {
54 |                     return false;
55 |                 }
56 |                 if (stack.pop() != '[') {
57 |                     return false;
58 |                 }
59 |             }
60 |         }
61 |         return stack.isEmpty();
62 |     }
63 | }
64 | 


--------------------------------------------------------------------------------
/Java/05.Java_Sort/Java_sort.java:
--------------------------------------------------------------------------------
 1 | import java.io.*;
 2 | import java.util.*;
 3 | 
 4 | 
 5 | class Student implements Comparable<Student> {
 6 |     
 7 |     private int id;
 8 |     private String fname;
 9 |     private double cgpa;
10 |     
11 |     public Student(int id, String fname, double cgpa) {
12 |         this.id = id;
13 |         this.fname = fname;
14 |         this.cgpa = cgpa;
15 |     }
16 |     
17 |     public int getId() {
18 |         return id;
19 |     }
20 |     
21 |     public String getFname() {
22 |         return fname;
23 |     }
24 |     
25 |     public double getCgpa() {
26 |         return cgpa;
27 |     }
28 |     
29 |     @Override
30 |     public int compareTo(Student anotherStudent) {
31 |         return Comparator.comparingDouble(Student::getCgpa)
32 |             .reversed()
33 |             .thenComparing(Student::getFname)
34 |             .thenComparingInt(Student::getId)
35 |             .compare(this, anotherStudent);
36 |     }
37 | }
38 | 
39 | public class Solution {
40 |     
41 |     public static void main(String[] args) {
42 |         List<Student> studentList = new ArrayList<Student>();
43 |         try (Scanner in = new Scanner(System.in)) {
44 |             int testCases = Integer.parseInt(in.nextLine());
45 |             while (testCases > 0) {
46 |                 int id = in.nextInt();
47 |                 String fname = in.next();
48 |                 double cgpa = in.nextDouble();
49 |             
50 |                 Student student = new Student(id, fname, cgpa);
51 |                 studentList.add(student);
52 |             
53 |                 testCases--;
54 |             }
55 |         }
56 |         Collections.sort(studentList);
57 |         studentList.forEach(student -> System.out.println(student.getFname()));
58 |     }
59 | }


--------------------------------------------------------------------------------
/Java/Object Oriented Programming/Java Abstract Class.java:
--------------------------------------------------------------------------------
 1 | // Problem :  https://www.hackerrank.com/challenges/java-abstract-class/problem
 2 | // Max Score: 10
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.util.*;
 7 | abstract class Book{
 8 | 	String title;
 9 | 	abstract void setTitle(String s);
10 | 	String getTitle(){
11 | 		return title;
12 | 	}
13 | }
14 | 
15 | class MyBook extends Book {
16 |     void setTitle(String s){
17 |         super.title = s;
18 |     }    
19 | }
20 | public class Main{
21 | 	
22 | 	public static void main(String []args){
23 | 		//Book new_novel=new Book(); This line prHMain.java:25: error: Book is abstract; cannot be instantiated
24 | 		Scanner sc=new Scanner(System.in);
25 | 		String title=sc.nextLine();
26 | 		MyBook new_novel=new MyBook();
27 | 		new_novel.setTitle(title);
28 | 		System.out.println("The title is: "+new_novel.getTitle());
29 |       	sc.close();
30 | 		
31 | 	}
32 | }
33 | 


--------------------------------------------------------------------------------
/Java/Object Oriented Programming/Java Inheritance I.java:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/java-inheritance-1/problem
 2 | // Max Score: 5
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.io.*;
 7 | import java.util.*;
 8 | import java.text.*;
 9 | import java.math.*;
10 | import java.util.regex.*;
11 | 
12 | class Animal{
13 | 	void walk(){
14 | 		System.out.println("I am walking");
15 | 	}
16 | }
17 | 
18 | class Bird extends Animal{
19 | 	void fly(){
20 | 		System.out.println("I am flying");
21 | 	}
22 |     	void sing(){
23 |           	System.out.println("I am singing"); 
24 |    	 }
25 | }
26 | 
27 | public class Solution{
28 | 
29 |    public static void main(String args[]){
30 | 
31 | 	  Bird bird = new Bird();
32 | 	  bird.walk();
33 | 	  bird.fly();
34 |       bird.sing();
35 | 	
36 |    }
37 | }
38 | 


--------------------------------------------------------------------------------
/Java/Object Oriented Programming/Java Inheritance II.java:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/java-inheritance-2/problem
 2 | // Max Score: 10
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.io.*;
 7 | import java.util.*;
 8 | import java.text.*;
 9 | import java.math.*;
10 | import java.util.regex.*;
11 | 
12 | 
13 | class Arithmetic {
14 |      int add(int a , int b){
15 |         return a+b;
16 |     }
17 | } 
18 |  class Adder extends Arithmetic{
19 | 
20 |  }
21 | public class Solution{
22 |     public static void main(String []args){
23 |         // Create a new Adder object
24 |         Adder a = new Adder();
25 |         
26 |         // Print the name of the superclass on a new line
27 |         System.out.println("My superclass is: " + a.getClass().getSuperclass().getName());	
28 |         
29 |         // Print the result of 3 calls to Adder's `add(int,int)` method as 3 space-separated integers:
30 |         System.out.print(a.add(10,32) + " " + a.add(10,3) + " " + a.add(10,10) + "\n");
31 |      }
32 | }
33 | 
34 | 


--------------------------------------------------------------------------------
/Java/Object Oriented Programming/Java Interface.java:
--------------------------------------------------------------------------------
 1 | /* Problem link -> https://www.hackerrank.com/challenges/java-interface/problem
 2 |     difficulty level -> easy
 3 |     points -> 10
 4 | */
 5 | 
 6 | 
 7 | 
 8 | import java.util.*;
 9 | interface AdvancedArithmetic{
10 |     int divisor_sum(int n);
11 | }
12 | 
13 | // Main code
14 | class MyCalculator implements AdvancedArithmetic {
15 |     public int divisor_sum(int n) {
16 |         if (n <= 1) { return n; }
17 | 
18 |         int res = n + 1;
19 |         for (int i = 2; i < n; i++) {
20 |             if (n % i == 0) {
21 |                 res += i;
22 |             }
23 |         }
24 | 
25 |         return res;
26 |     }
27 | }
28 | 
29 | 
30 | 
31 | class java_interface{         // already present in hackerrank website
32 |     public static void main(String []args){
33 |         MyCalculator my_calculator = new MyCalculator();
34 |         System.out.print("I implemented: ");
35 |         ImplementedInterfaceNames(my_calculator);
36 |         Scanner sc = new Scanner(System.in);
37 |         int n = sc.nextInt();
38 |         System.out.print(my_calculator.divisor_sum(n) + "\n");
39 |         sc.close();
40 |     }
41 |     /*
42 |      *  ImplementedInterfaceNames method takes an object and prints the name of the interfaces it implemented
43 |      */
44 |     static void ImplementedInterfaceNames(Object o){
45 |         Class[] theInterfaces = o.getClass().getInterfaces();
46 |         for (int i = 0; i < theInterfaces.length; i++){
47 |             String interfaceName = theInterfaces[i].getName();
48 |             System.out.println(interfaceName);
49 |         }
50 |     }
51 | }


--------------------------------------------------------------------------------
/Java/Object Oriented Programming/Java Method Overriding.java:
--------------------------------------------------------------------------------
 1 | // Problem :  https://www.hackerrank.com/challenges/java-method-overriding
 2 | // Max Score: 10
 3 | // Difficulty: Easy
 4 | // Language: Java
 5 | 
 6 | import java.util.*;
 7 | class Sports{
 8 | 
 9 |     String getName(){
10 |         return "Generic Sports";
11 |     }
12 |   
13 |     void getNumberOfTeamMembers(){
14 |         System.out.println( "Each team has n players in " + getName() );
15 |     }
16 | }
17 | 
18 | class Soccer extends Sports{
19 |     @Override
20 |     String getName(){
21 |         return "Soccer Class";
22 |     }
23 |     @Override
24 |     void getNumberOfTeamMembers(){
25 |         System.out.println( "Each team has 11 players in " + getName());
26 |     }
27 |     
28 | }
29 | 
30 | public class Solution{
31 | 	
32 |     public static void main(String []args){
33 |         Sports c1 = new Sports();
34 |         Soccer c2 = new Soccer();
35 |         System.out.println(c1.getName());
36 |         c1.getNumberOfTeamMembers();
37 |         System.out.println(c2.getName());
38 |         c2.getNumberOfTeamMembers();
39 | 	}
40 | }
41 | 
42 | 


--------------------------------------------------------------------------------
/Java/sorting/bubblesort.java:
--------------------------------------------------------------------------------
 1 | public class bubblesort {
 2 |     public static void bub(int arr[])
 3 |     {
 4 |         for(int turn=0;turn<arr.length;turn++){
 5 |             for(int j=0;j<arr.length-1-turn;j++){
 6 |                 if(arr[j]>arr[j+1]){
 7 |                     int temp=arr[j];
 8 |                     arr[j]=arr[j+1];
 9 |                     arr[j+1]=temp;
10 |                 }
11 |             }
12 |         }
13 |     }
14 |     public static void printarr(int arr[]){
15 |         for(int i=0;i<arr.length;i++){
16 |             System.out.print(arr[i]+" ");
17 |         }
18 |         System.out.println();
19 |     }
20 |     
21 |     public static void main(String args[]){
22 |     int arr[] = {1,4,1,3,2,4,3,7};
23 | 
24 |     bub(arr);
25 |     printarr(arr);
26 |     }
27 | }
28 | 


--------------------------------------------------------------------------------
/Java/sorting/countingsort.java:
--------------------------------------------------------------------------------
 1 | public class countingsort {
 2 |     public static void printarr(int arr[]){
 3 |         for(int i=0;i<arr.length;i++){
 4 |             System.out.print(arr[i]+" ");
 5 |         }
 6 |         System.out.println();
 7 |     }
 8 | 
 9 |     public static void count(int arr[]){
10 |         int largest=Integer.MIN_VALUE;
11 |     for(int i=0;i<arr.length;i++){
12 |         largest=Math.max(largest,arr[i]);
13 |     }
14 |              int count[]=new int[largest+1];
15 |              for(int i=0;i<arr.length;i++){
16 |                 count[arr[i]]++;
17 |              }
18 |              //sorting
19 |              int j=0;
20 |              for(int i=0;i<count.length;i++){
21 |                 while(count[i]>0){
22 |                     arr[j]=i;
23 |                     j++;
24 |                     count[i]--;
25 |                 }
26 |     
27 |              }
28 |     }
29 |     
30 |         public static void main(String args[]){
31 |         int arr[] = {1,4,1,3,2,4,3,7};
32 | 
33 |         count(arr);
34 |         printarr(arr);
35 |         }
36 | }
37 | 


--------------------------------------------------------------------------------
/Java/sorting/insertionsort.java:
--------------------------------------------------------------------------------
 1 | public class insertionsort {
 2 |     public static void printarr(int arr[]){
 3 |         for(int i=0;i<arr.length;i++){
 4 |             System.out.print(arr[i]+" ");
 5 |         }
 6 |         System.out.println();
 7 |     }
 8 |     
 9 | public static void insertion(int arr[]){
10 |     for(int i=1;i<arr.length;i++){
11 |         int curr=arr[i];
12 |         int prev=i-1;
13 |         while(prev>=0 && arr[prev]>curr){
14 |             arr[prev+1]=arr[prev];
15 |             prev--;
16 |         }
17 |         //insertion
18 |         arr[prev+1]=curr;
19 |      }
20 | }
21 |     public static void main(String args[]){
22 |     int arr[] = {1,4,1,3,2,4,3,7};
23 |     insertion(arr);
24 |     printarr(arr);
25 |     }
26 | }
27 | 


--------------------------------------------------------------------------------
/Java/sorting/selectionsort.java:
--------------------------------------------------------------------------------
 1 | public class selectionsort {
 2 |     public static void printarr(int arr[]){
 3 |         for(int i=0;i<arr.length;i++){
 4 |             System.out.print(arr[i]+" ");
 5 |         }
 6 |         System.out.println();
 7 |     }
 8 |     public static void select(int arr[]){
 9 |         for(int i=0;i<arr.length-1;i++){
10 |             int minpos=i;
11 |             for(int j=i+1;j<arr.length;j++){
12 |                 if(arr[minpos]>arr[j]){
13 |                     minpos=j;
14 |                 }
15 |             }
16 |             int temp=arr[minpos];
17 |                     arr[minpos]=arr[i];
18 |                     arr[i]=temp;
19 |         }
20 | }
21 |     public static void main(String args[]){
22 |     int arr[] = {1,4,1,3,2,4,3,7};
23 |     select(arr);
24 |     
25 |     printarr(arr);
26 |     }
27 | }
28 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2021 Riddhi Bhagat
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


--------------------------------------------------------------------------------
/Problem Solving/Algorithms/Bit Manipulation/Maximizing_XOR.cpp:
--------------------------------------------------------------------------------
 1 | /*
 2 | Maximizing_XOR
 3 | Category: Bit Manipulation
 4 | Difficulty: Easy
 5 | Max Score: 30
 6 | */
 7 | #include <bits/stdc++.h>
 8 | 
 9 | using namespace std;
10 | 
11 | string ltrim(const string &);
12 | string rtrim(const string &);
13 | 
14 | /*
15 |  * Complete the 'maximizingXor' function below.
16 |  *
17 |  * The function is expected to return an INTEGER.
18 |  * The function accepts following parameters:
19 |  *  1. INTEGER l
20 |  *  2. INTEGER r
21 |  */
22 | 
23 | int maximizingXor(int l, int r) {
24 |     vector<int>v;
25 |     for(int i=l;i<r;i++){
26 |         for(int j=l+1;j<=r;j++){
27 |             int x=i^j;
28 |             v.push_back(x);
29 |         }
30 |     }
31 |     sort(v.begin(),v.end());
32 |     return v.back();
33 | }
34 | 
35 | int main()
36 | {
37 |     ofstream fout(getenv("OUTPUT_PATH"));
38 | 
39 |     string l_temp;
40 |     getline(cin, l_temp);
41 | 
42 |     int l = stoi(ltrim(rtrim(l_temp)));
43 | 
44 |     string r_temp;
45 |     getline(cin, r_temp);
46 | 
47 |     int r = stoi(ltrim(rtrim(r_temp)));
48 | 
49 |     int result = maximizingXor(l, r);
50 | 
51 |     fout << result << "\n";
52 | 
53 |     fout.close();
54 | 
55 |     return 0;
56 | }
57 | 
58 | string ltrim(const string &str) {
59 |     string s(str);
60 | 
61 |     s.erase(
62 |         s.begin(),
63 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
64 |     );
65 | 
66 |     return s;
67 | }
68 | 
69 | string rtrim(const string &str) {
70 |     string s(str);
71 | 
72 |     s.erase(
73 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
74 |         s.end()
75 |     );
76 | 
77 |     return s;
78 | }
79 | 


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/Problem Solving/Algorithms/Dynamic Programming/Equal/Equal.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link :https://www.hackerrank.com/challenges/equal/problem?isFullScreen=true
 2 | // Score: 30
 3 | // Difficulty: Medium
 4 | 
 5 | #include<cassert>
 6 | #include<iostream>
 7 | #include<algorithm>
 8 | using namespace std;
 9 |     
10 | int T, N;
11 | int d[100010];
12 |     
13 | int main() {
14 |     cin >> T;
15 |     assert(T <= 100);
16 |     while(T--) {
17 |         cin >> N;
18 |         assert(N <= 10000);
19 |         for(int i = 0; i < N; i++) 
20 |         {cin >> d[i]; assert(d[i] < 1000);}
21 |         int M = *min_element(d, d + N);//finding the minimum element
22 |         int r = 1e9; //just an upper limit
23 |         for(int t = M - 4; t <= M; t++) {
24 |             int s = 0;
25 |             for(int i = 0; i < N; i++) {
26 |                 int D = d[i] - t;
27 |                 s += D / 5, D %= 5;//we are trying to find the number of times the given number be divivisible by 5->gives no of opertations
28 |                 s += D / 2, D %= 2;//same with 2 and 1 from the remainder
29 |                 s += D;
30 |             }
31 |             r = min(r, s); //just an upperlimit for testing
32 |         }
33 |         cout << r << endl;
34 |     }
35 |     return 0;
36 | }
37 | 


--------------------------------------------------------------------------------
/Problem Solving/Algorithms/Dynamic Programming/Stock Maximize/Stock Maximize.cpp:
--------------------------------------------------------------------------------
  1 | // Problem Link :https://www.hackerrank.com/challenges/stockmax/problem?isFullScreen=true
  2 | // Score: 50
  3 | // Difficulty: Medium
  4 | 
  5 | #include <bits/stdc++.h>
  6 | 
  7 | using namespace std;
  8 | 
  9 | string ltrim(const string &);
 10 | string rtrim(const string &);
 11 | vector<string> split(const string &);
 12 | 
 13 | /*
 14 |  * Complete the 'stockmax' function below.
 15 |  *
 16 |  * The function is expected to return a LONG_INTEGER.
 17 |  * The function accepts INTEGER_ARRAY prices as parameter.
 18 |  */
 19 | 
 20 | long stockmax(vector<int> prices) {
 21 | int n= prices.size();
 22 | int i;
 23 | long k=0,temp=0;
 24 | 
 25 | temp = prices[n-1];
 26 | 
 27 | // explanation-you are trying to move from right end to left end of the array so as to find the local maximum for that part
 28 | for(i=n-1;i>=0;i--){
 29 |     if(prices[i]>temp)
 30 |         {
 31 |             temp=prices[i];
 32 |         }
 33 |     k+= temp-prices[i];
 34 | }
 35 | return k;
 36 | }
 37 | 
 38 | int main()
 39 | {
 40 |     ofstream fout(getenv("OUTPUT_PATH"));
 41 | 
 42 |     string t_temp;
 43 |     getline(cin, t_temp);
 44 | 
 45 |     int t = stoi(ltrim(rtrim(t_temp)));
 46 | 
 47 |     for (int t_itr = 0; t_itr < t; t_itr++) {
 48 |         string n_temp;
 49 |         getline(cin, n_temp);
 50 | 
 51 |         int n = stoi(ltrim(rtrim(n_temp)));
 52 | 
 53 |         string prices_temp_temp;
 54 |         getline(cin, prices_temp_temp);
 55 | 
 56 |         vector<string> prices_temp = split(rtrim(prices_temp_temp));
 57 | 
 58 |         vector<int> prices(n);
 59 | 
 60 |         for (int i = 0; i < n; i++) {
 61 |             int prices_item = stoi(prices_temp[i]);
 62 | 
 63 |             prices[i] = prices_item;
 64 |         }
 65 | 
 66 |         long result = stockmax(prices);
 67 | 
 68 |         fout << result << "\n";
 69 |     }
 70 | 
 71 |     fout.close();
 72 | 
 73 |     return 0;
 74 | }
 75 | 
 76 | string ltrim(const string &str) {
 77 |     string s(str);
 78 | 
 79 |     s.erase(
 80 |         s.begin(),
 81 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
 82 |     );
 83 | 
 84 |     return s;
 85 | }
 86 | 
 87 | string rtrim(const string &str) {
 88 |     string s(str);
 89 | 
 90 |     s.erase(
 91 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
 92 |         s.end()
 93 |     );
 94 | 
 95 |     return s;
 96 | }
 97 | 
 98 | vector<string> split(const string &str) {
 99 |     vector<string> tokens;
100 | 
101 |     string::size_type start = 0;
102 |     string::size_type end = 0;
103 | 
104 |     while ((end = str.find(" ", start)) != string::npos) {
105 |         tokens.push_back(str.substr(start, end - start));
106 | 
107 |         start = end + 1;
108 |     }
109 | 
110 |     tokens.push_back(str.substr(start));
111 | 
112 |     return tokens;
113 | }
114 | 


--------------------------------------------------------------------------------
/Problem Solving/Algorithms/Dynamic Programming/The Coin Change Problem/The Coin Change Problem.cpp:
--------------------------------------------------------------------------------
 1 | // Problem Link :https://www.hackerrank.com/challenges/coin-change/problem?isFullScreen=true
 2 | // Score: 60
 3 | // Difficulty: Medium
 4 | 
 5 | #include<bits/stdc++.h>
 6 | using namespace std;
 7 | 
 8 | int c[52];
 9 | int numCoins;
10 | long long table[52][252];//memorization table
11 | bool calculated[52][252];
12 | 
13 | // this problem is solved using recurision tree method
14 | 
15 | long long solve(int i, int make)
16 | {
17 |     if(make<0) return 0; //exit tree-node#0
18 |     if(make==0)return 1; //exit tree-node#1
19 |     if(i > numCoins) return 0; 
20 |     if(calculated[i][make] == false){ //eliminating overlap
21 |         table[i][make] = solve(i, make - c[i]) + solve(i+1, make); //recursion function  //logic is you care counting minimum possible ways from scratch
22 |         calculated[i][make] = true;
23 |     }
24 |     return table[i][make];
25 | }
26 | int main(){
27 | 
28 |     int make;
29 |     cin>>make>>numCoins;
30 |     for(int i=1;i<=numCoins;i++){
31 |         cin>>c[i];
32 |     }
33 |     cout<<solve(1, make)<<endl;
34 |     return 0;
35 | }
36 | 


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/Problem Solving/Algorithms/Recursion/Crossword Puzzle/dummy.py:
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1 | # This file has to be deleted.


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/Problem Solving/Algorithms/Recursion/Recursive Digit Sum/Recursive Digit Sum.cpp:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/recursive-digit-sum/problem
 2 | // Score: 30
 3 | // Difficulty : Medium
 4 | 
 5 | 
 6 | #include <bits/stdc++.h>
 7 | 
 8 | using namespace std;
 9 | 
10 | string ltrim(const string &);
11 | string rtrim(const string &);
12 | vector<string> split(const string &);
13 | 
14 | /*
15 |  * Complete the 'superDigit' function below.
16 |  *
17 |  * The function is expected to return an INTEGER.
18 |  * The function accepts following parameters:
19 |  *  1. STRING n
20 |  *  2. INTEGER k
21 |  */
22 | int superDigit(string n, int k) {
23 |     long super = 0;
24 |     for (char& c : n)
25 |         super += c - '0';
26 | 
27 |     super *= k;
28 |     if (super <= 9) return super;
29 |     return superDigit(to_string(super), 1);
30 | }
31 | 
32 | int main()
33 | {
34 |     ofstream fout(getenv("OUTPUT_PATH"));
35 | 
36 |     string first_multiple_input_temp;
37 |     getline(cin, first_multiple_input_temp);
38 | 
39 |     vector<string> first_multiple_input = split(rtrim(first_multiple_input_temp));
40 | 
41 |     string n = first_multiple_input[0];
42 | 
43 |     int k = stoi(first_multiple_input[1]);
44 | 
45 |     int result = superDigit(n, k);
46 | 
47 |     fout << result << "\n";
48 | 
49 |     fout.close();
50 | 
51 |     return 0;
52 | }
53 | 
54 | string ltrim(const string &str) {
55 |     string s(str);
56 | 
57 |     s.erase(
58 |         s.begin(),
59 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
60 |     );
61 | 
62 |     return s;
63 | }
64 | 
65 | string rtrim(const string &str) {
66 |     string s(str);
67 | 
68 |     s.erase(
69 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
70 |         s.end()
71 |     );
72 | 
73 |     return s;
74 | }
75 | 
76 | vector<string> split(const string &str) {
77 |     vector<string> tokens;
78 | 
79 |     string::size_type start = 0;
80 |     string::size_type end = 0;
81 | 
82 |     while ((end = str.find(" ", start)) != string::npos) {
83 |         tokens.push_back(str.substr(start, end - start));
84 | 
85 |         start = end + 1;
86 |     }
87 | 
88 |     tokens.push_back(str.substr(start));
89 | 
90 |     return tokens;
91 | }


--------------------------------------------------------------------------------
/Problem Solving/Algorithms/Recursion/Recursive Digit Sum/Recursive Digit Sum.java:
--------------------------------------------------------------------------------
 1 | // Problem : https://www.hackerrank.com/challenges/recursive-digit-sum/problem
 2 | // Score: 30
 3 | // Difficulty : Medium
 4 | 
 5 | import java.io.*;
 6 | import java.math.*;
 7 | import java.security.*;
 8 | import java.text.*;
 9 | import java.util.*;
10 | import java.util.concurrent.*;
11 | import java.util.function.*;
12 | import java.util.regex.*;
13 | import java.util.stream.*;
14 | import static java.util.stream.Collectors.joining;
15 | import static java.util.stream.Collectors.toList;
16 | 
17 | class Result {
18 | 
19 |     /*
20 |      * Complete the 'superDigit' function below.
21 |      *
22 |      * The function is expected to return an INTEGER.
23 |      * The function accepts following parameters:
24 |      *  1. STRING n
25 |      *  2. INTEGER k
26 |      */
27 | 
28 |     public static int superDigit(String n, int k) {
29 |     // Write your code here
30 |         long s = 0L;
31 |         for(int i=0;i<n.length();i++){
32 |             s += n.charAt(i) - '0';
33 |         }
34 |         s *= k;
35 |         if(s<=9){
36 |             return (int)s;
37 |         }
38 |         return superDigit(Long.toString(s),1);
39 |     }
40 | 
41 | }
42 | 
43 | public class Solution {
44 |     public static void main(String[] args) throws IOException {
45 |         BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
46 |         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
47 | 
48 |         String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");
49 | 
50 |         String n = firstMultipleInput[0];
51 | 
52 |         int k = Integer.parseInt(firstMultipleInput[1]);
53 | 
54 |         int result = Result.superDigit(n, k);
55 | 
56 |         bufferedWriter.write(String.valueOf(result));
57 |         bufferedWriter.newLine();
58 | 
59 |         bufferedReader.close();
60 |         bufferedWriter.close();
61 |     }
62 | }
63 | 


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/Problem Solving/Algorithms/Recursion/Recursive Digit Sum/Recursive Digit Sum.py:
--------------------------------------------------------------------------------
 1 | #  Problem : https://www.hackerrank.com/challenges/recursive-digit-sum/problem
 2 | #  Score: 30
 3 | #  Difficulty : Medium
 4 | 
 5 | #!/bin/python3
 6 | 
 7 | import math
 8 | import os
 9 | import random
10 | import re
11 | import sys
12 | 
13 | #
14 | # Complete the 'superDigit' function below.
15 | #
16 | # The function is expected to return an INTEGER.
17 | # The function accepts following parameters:
18 | #  1. STRING n
19 | #  2. INTEGER k
20 | #
21 | 
22 | def superDigit(n, k):
23 |     # Write your code here
24 |     s = 0
25 |     for x in n:
26 |         s+=int(x)
27 |     s*=k;
28 |     if s<=9:
29 |         return s;
30 |     return superDigit(str(s),1)
31 | 
32 | if __name__ == '__main__':
33 |     fptr = open(os.environ['OUTPUT_PATH'], 'w')
34 | 
35 |     first_multiple_input = input().rstrip().split()
36 | 
37 |     n = first_multiple_input[0]
38 | 
39 |     k = int(first_multiple_input[1])
40 | 
41 |     result = superDigit(n, k)
42 | 
43 |     fptr.write(str(result) + '\n')
44 | 
45 |     fptr.close()
46 | 


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/Problem Solving/Algorithms/Recursion/The Power Sum/dummy.cpp:
--------------------------------------------------------------------------------
1 | //This file has to be deleted.


--------------------------------------------------------------------------------
/Problem Solving/Algorithms/Recursion/The Power Sum/power.py:
--------------------------------------------------------------------------------
 1 | ## Problem Link = > https://www.hackerrank.com/challenges/the-power-sum/problem?h_r=profile
 2 | ## Problem Name => The Power Sum
 3 | ## Language => Python
 4 | ## Max Score => 20
 5 | ## Difficulty => Medium
 6 | #!/bin/python3
 7 | 
 8 | import math
 9 | import os
10 | import random
11 | import re
12 | import sys
13 | 
14 | #
15 | # Complete the 'powerSum' function below.
16 | #
17 | # The function is expected to return an INTEGER.
18 | # The function accepts following parameters:
19 | #  1. INTEGER X
20 | #  2. INTEGER N
21 | #
22 | 
23 | def solution(arr,x,n):
24 |     if x==0:
25 |         return 1
26 |     if len(arr)==0:
27 |         return 0 
28 |     if x<0:
29 |         return 0
30 |     sol=solution(arr[1:],x-arr[0]**n,n)+solution(arr[1:],x,n)
31 |     return sol
32 | def powerSum(X, N):
33 |     baseIndex=[]
34 |     for i in range(int(pow(X,(1/N)))):
35 |         baseIndex.append(i+1)
36 |     answer=solution(baseIndex,X,N)
37 |     return answer    
38 |         
39 |     
40 | 
41 | if __name__ == '__main__':
42 |     fptr = open(os.environ['OUTPUT_PATH'], 'w')
43 | 
44 |     X = int(input().strip())
45 | 
46 |     N = int(input().strip())
47 | 
48 |     result = powerSum(X, N)
49 | 
50 |     fptr.write(str(result) + '\n')
51 | 
52 |     fptr.close()
53 | 


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/Problem Solving/Algorithms/Searching/Array Solution/Array Solution.cpp:
--------------------------------------------------------------------------------
  1 | // Problem: https://www.hackerrank.com/challenges/sherlock-and-array/problem
  2 | // Score: 40
  3 | // Difficulty: Easy
  4 | 
  5 | #include <bits/stdc++.h>
  6 | 
  7 | using namespace std;
  8 | 
  9 | string ltrim(const string &);
 10 | string rtrim(const string &);
 11 | vector<string> split(const string &);
 12 | 
 13 | /*
 14 |  * Complete the 'balancedSums' function below.
 15 |  *
 16 |  * The function is expected to return a STRING.
 17 |  * The function accepts INTEGER_ARRAY arr as parameter.
 18 |  */
 19 | 
 20 | string balancedSums(vector<int> arr) {
 21 |     int n=arr.size();
 22 |     int sum=0;
 23 |     for(int i=0;i<n;i++)
 24 |     {
 25 |         sum+=arr[i];
 26 |     }
 27 |     int left=0;
 28 |     for(int i=0;i<n;i++)
 29 |     {
 30 |         if(2*left==sum-arr[i])
 31 |         {
 32 |             return "YES";
 33 |         }
 34 |         left+=arr[i];
 35 |     }
 36 |     return "NO";
 37 | }
 38 | 
 39 | int main()
 40 | {
 41 |     ofstream fout(getenv("OUTPUT_PATH"));
 42 | 
 43 |     string T_temp;
 44 |     getline(cin, T_temp);
 45 | 
 46 |     int T = stoi(ltrim(rtrim(T_temp)));
 47 | 
 48 |     for (int T_itr = 0; T_itr < T; T_itr++) {
 49 |         string n_temp;
 50 |         getline(cin, n_temp);
 51 | 
 52 |         int n = stoi(ltrim(rtrim(n_temp)));
 53 | 
 54 |         string arr_temp_temp;
 55 |         getline(cin, arr_temp_temp);
 56 | 
 57 |         vector<string> arr_temp = split(rtrim(arr_temp_temp));
 58 | 
 59 |         vector<int> arr(n);
 60 | 
 61 |         for (int i = 0; i < n; i++) {
 62 |             int arr_item = stoi(arr_temp[i]);
 63 | 
 64 |             arr[i] = arr_item;
 65 |         }
 66 | 
 67 |         string result = balancedSums(arr);
 68 | 
 69 |         fout << result << "\n";
 70 |     }
 71 | 
 72 |     fout.close();
 73 | 
 74 |     return 0;
 75 | }
 76 | 
 77 | string ltrim(const string &str) {
 78 |     string s(str);
 79 | 
 80 |     s.erase(
 81 |         s.begin(),
 82 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
 83 |     );
 84 | 
 85 |     return s;
 86 | }
 87 | 
 88 | string rtrim(const string &str) {
 89 |     string s(str);
 90 | 
 91 |     s.erase(
 92 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
 93 |         s.end()
 94 |     );
 95 | 
 96 |     return s;
 97 | }
 98 | 
 99 | vector<string> split(const string &str) {
100 |     vector<string> tokens;
101 | 
102 |     string::size_type start = 0;
103 |     string::size_type end = 0;
104 | 
105 |     while ((end = str.find(" ", start)) != string::npos) {
106 |         tokens.push_back(str.substr(start, end - start));
107 | 
108 |         start = end + 1;
109 |     }
110 | 
111 |     tokens.push_back(str.substr(start));
112 | 
113 |     return tokens;
114 | }
115 | 


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/Problem Solving/Data Structures/Array/Left Rotation/Left Rotation.java:
--------------------------------------------------------------------------------
 1 | // Problem Link: https://www.hackerrank.com/challenges/array-left-rotation/problem
 2 | // Problem: Left Rotation
 3 | // Language: Java
 4 | // Subdomain: Arrays
 5 | // Difficulty: Easy
 6 | // Max Score: 20
 7 | 
 8 | import java.io.*;
 9 | import java.math.*;
10 | import java.security.*;
11 | import java.text.*;
12 | import java.util.*;
13 | import java.util.concurrent.*;
14 | import java.util.function.*;
15 | import java.util.regex.*;
16 | import java.util.stream.*;
17 | import static java.util.stream.Collectors.joining;
18 | import static java.util.stream.Collectors.toList;
19 | 
20 | class Result {
21 | 
22 |     /*
23 |      * Complete the 'rotateLeft' function below.
24 |      *
25 |      * The function is expected to return an INTEGER_ARRAY.
26 |      * The function accepts following parameters:
27 |      *  1. INTEGER d
28 |      *  2. INTEGER_ARRAY arr
29 |      */
30 | 
31 |     public static void helpRotate(int s, int e, List < Integer > arr) {
32 |         while (s < e) {
33 |             int temp = arr.get(s);
34 |             arr.set(s, arr.get(e));
35 |             arr.set(e, temp);
36 |             s++;
37 |             e--;
38 |         }
39 |     }
40 | 
41 |     public static List < Integer > rotateLeft(int d, List < Integer > arr) {
42 |         int n = arr.size();
43 |         d %= n;
44 |         helpRotate(0, n - 1, arr);
45 |         helpRotate(0, n - 1 - d, arr);
46 |         helpRotate(n - d, n - 1, arr);
47 |         return arr;
48 |     }
49 | 
50 | }
51 | 
52 | public class Solution {
53 |     public static void main(String[] args) throws IOException {
54 |         BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
55 |         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
56 | 
57 |         String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");
58 | 
59 |         int n = Integer.parseInt(firstMultipleInput[0]);
60 | 
61 |         int d = Integer.parseInt(firstMultipleInput[1]);
62 | 
63 |         List < Integer > arr = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
64 |             .map(Integer::parseInt)
65 |             .collect(toList());
66 | 
67 |         List < Integer > result = Result.rotateLeft(d, arr);
68 | 
69 |         bufferedWriter.write(
70 |             result.stream()
71 |             .map(Object::toString)
72 |             .collect(joining(" ")) +
73 |             "\n"
74 |         );
75 | 
76 |         bufferedReader.close();
77 |         bufferedWriter.close();
78 |     }
79 | }
80 | 


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/Problem Solving/Data Structures/Stacks/Balanced Brackets/Balanced Brackets.cpp:
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 1 | // Problem Link: https://www.hackerrank.com/challenges/balanced-brackets/problem
 2 | // Problem: Balance Brackets
 3 | // Language: C++
 4 | // Subdomain: Data Structures
 5 | // Difficulty: Medium
 6 | // Max Score: 25
 7 | 
 8 | #include <bits/stdc++.h>
 9 | 
10 | using namespace std;
11 | 
12 | string ltrim(const string &);
13 | string rtrim(const string &);
14 | 
15 | /*
16 |  * Complete the 'isBalanced' function below.
17 |  *
18 |  * The function is expected to return a STRING.
19 |  * The function accepts STRING s as parameter.
20 |  */
21 | 
22 | unordered_map<char, int> mp={{'{', -3}, {'[', -2}, {'(', -1},{')', 1}, {']', 2},{'}', 3}};
23 | 
24 | string isBalanced(string s){
25 |     stack<char> st;
26 |     for(auto c: s){
27 |         if(mp[c]<0){
28 |             st.push(c);
29 |         }
30 |         else{
31 |             if(st.empty()) return "NO";
32 |             if(mp[st.top()]+mp[c]!=0) {
33 |                 return "NO";
34 |             }
35 |             st.pop();
36 |         }
37 |     }
38 |     if(st.empty()) return "YES";
39 |     return "NO";
40 | }
41 | int main()
42 | {
43 |     ofstream fout(getenv("OUTPUT_PATH"));
44 | 
45 |     string t_temp;
46 |     getline(cin, t_temp);
47 | 
48 |     int t = stoi(ltrim(rtrim(t_temp)));
49 | 
50 |     for (int t_itr = 0; t_itr < t; t_itr++) {
51 |         string s;
52 |         getline(cin, s);
53 | 
54 |         string result = isBalanced(s);
55 | 
56 |         fout << result << "\n";
57 |     }
58 | 
59 |     fout.close();
60 | 
61 |     return 0;
62 | }
63 | 
64 | string ltrim(const string &str) {
65 |     string s(str);
66 | 
67 |     s.erase(
68 |         s.begin(),
69 |         find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
70 |     );
71 | 
72 |     return s;
73 | }
74 | 
75 | string rtrim(const string &str) {
76 |     string s(str);
77 | 
78 |     s.erase(
79 |         find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
80 |         s.end()
81 |     );
82 | 
83 |     return s;
84 | }
85 | 


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/Python/01. Introduction/Loops.py:
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1 | # Solves python loops problem: https://www.hackerrank.com/challenges/python-loops/problem?isFullScreen=true
2 | # Difficulty: Easy
3 | # Max Score: 10
4 | 
5 | if __name__ == '__main__':
6 |     n = int(input()) #Takes input
7 |     for i in range(n): #Runs the loop from 0 to n-1
8 |         print(i**2)  #prints their squares


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/Python/01. Introduction/Python Division.py:
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 1 | # Problem: https://www.hackerrank.com/challenges/python-division/problem?isFullScreen=true
 2 | # Score: 10
 3 | # dificulty: Easy
 4 | 
 5 | if __name__ == '__main__':
 6 |     a = int(input())
 7 |     b = int(input())
 8 |     
 9 |     print(a//b) # integer division
10 |     print(a/b) # float division
11 |     


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/Python/01. Introduction/Python If-Else.py:
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 1 | # Hackerrank Problem link: https://www.hackerrank.com/challenges/py-if-else/problem
 2 | # Score: 10.0
 3 | # Difficulty: Easy
 4 | 
 5 | import math
 6 | import os
 7 | import random
 8 | import re
 9 | import sys
10 | 
11 | 
12 | 
13 | if __name__ == '__main__':
14 |     n = int(input().strip())
15 |     if n%2==1:
16 |         print("Weird")
17 |     elif n%2==0 and n>=2 and n<=5:
18 |         print("Not Weird")
19 |     elif n%2==0 and n>=6 and n<=20:
20 |         print("Weird")
21 |     elif n%2==0 and n>20:
22 |         print("Not Weird")
23 | 


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/Python/01. Introduction/Write a function.py:
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 1 | # Problem : https://www.hackerrank.com/challenges/write-a-function/problem?isFullScreen=true
 2 | # Score : 10
 3 | # Difficulty : Medium
 4 | 
 5 | 
 6 | def is_leap(year):
 7 |     leap = False
 8 |     if not year % 100 :
 9 |         if not year % 400 :
10 |             leap = True
11 |     elif not year % 4 :
12 |         leap = True    
13 |     return leap
14 | 
15 | year = int(input())
16 | print(is_leap(year))


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/Python/02. Basic Data Types/Find the Runner-Up Score.py:
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 1 | # Problem: https://www.hackerrank.com/challenges/find-second-maximum-number-in-a-list/problem
 2 | # Score: 10
 3 | # Difficulty: Easy
 4 | 
 5 | if __name__ == '__main__':
 6 |     n = int(input())
 7 |     arr = map(int, input().split())
 8 | 
 9 | list_arr = list(arr)
10 | 
11 | print(
12 |     max([x for x in list_arr if x != max(list_arr)])
13 | )
14 | 


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/Python/02. Basic Data Types/Finding The Percentage.py:
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 1 | # Problem: https://www.hackerrank.com/challenges/finding-the-percentage/problem?isFullScreen=true
 2 | # Score: 10
 3 | # Difficulty : Easy
 4 | 
 5 | if __name__ == '__main__':
 6 |     n = int(input())
 7 |     student_marks = {}
 8 |     for _ in range(n):
 9 |         name, *line = input().split()
10 |         scores = list(map(float, line))
11 |         student_marks[name] = scores
12 |     query_name = input()
13 | final = list(student_marks[query_name])
14 | percentage = sum(final)/len(final)
15 | print("%.2f" % percentage)


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/Python/02. Basic Data Types/List Comprehensions.py:
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 1 | # Problem : https://www.hackerrank.com/challenges/list-comprehensions/problem?isFullScreen=false
 2 | # Score : 10
 3 | # Difficulty : Easy
 4 | 
 5 | if __name__ == '__main__':
 6 |     x = int(input())
 7 |     y = int(input())
 8 |     z = int(input())
 9 |     n = int(input())
10 |     lst=[]
11 |     for i in range(x+1):
12 |         for j in range(y+1):
13 |             for k in range(z+1):
14 |                 if(i+j+k)!=n:
15 |                     lst.append([i,j,k])
16 |     print(lst)


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/Python/03. Strings/StringValidators.py:
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 1 | 
 2 | //-- # Problem : https://www.hackerrank.com/challenges/string-validators/problem
 3 | 
 4 | //-- # Score : 10
 5 | 
 6 | //-- # Difficulty : Easy
 7 | 
 8 | if __name__ == "__main__":
 9 |     s = input()
10 |     #it checks all the characters of a string alphanumeric
11 |     print(any(i.isalnum() for i in s))
12 |     #it checks all the characters of a string are alphabetical
13 |     print(any(i.isalpha() for i in s))
14 |     #it checks all the characters of a string are digits
15 |     print(any(i.isdigit() for i in s))
16 |     #it checks all the characters of a string are lowercase characters
17 |     print(any(i.islower() for i in s))
18 |     #it checks all the characters of a string are uppercase characters
19 |     print(any(i.isupper() for i in s))
20 | 
21 | 


--------------------------------------------------------------------------------
/Python/03. Strings/dummy.py:
--------------------------------------------------------------------------------
1 | # this file has ro be deleted


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/Python/03. Strings/sWAP_cASE.py:
--------------------------------------------------------------------------------
 1 | """
 2 | 
 3 | //-- # Problem : https://www.hackerrank.com/challenges/swap-case/problem
 4 | 
 5 | //-- # Score : 10
 6 | 
 7 | //-- # Difficulty : Easy
 8 | 
 9 | """
10 | 
11 | 
12 | def swap_case(s):
13 |     """
14 |     Swap case method: map the input string
15 |     changing each letter to its opposite case,
16 |     after that, convert the output to string
17 |     """
18 |     return "".join(map(lambda l: l.upper() if l.islower() else l.lower(), s))
19 | 
20 | 
21 | if __name__ == "__main__":
22 |     s = input()
23 |     result = swap_case(s)
24 |     print(result)
25 | 


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/Python/04. Sets/No Idea!.py:
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 1 |  #Problem Link : https://www.hackerrank.com/challenges/no-idea/problem?isFullScreen=true
 2 |  # Problem : No Idea!
 3 |  # Language : Python
 4 |  # Subdomain : Sets
 5 |  # Max Score : 50
 6 |  # Difficulty : Medium
 7 | 
 8 | io = input().split()
 9 | m = int(io[0])
10 | n = int(io[1])
11 | 
12 | storage = list()
13 | count = 0
14 | 
15 | storage = list(map(int, input().strip().split()))
16 | 
17 | A = set(map(int, input().strip().split()))
18 | B = set(map(int, input().strip().split()))
19 | 
20 | for i in storage:
21 |     if i in A:
22 |         count = count+1
23 |     if i in B:
24 |         count = count-1
25 | 
26 | print(count)
27 | 


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/Python/Debugging/Words Score.py:
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 1 | #Problem Statement- https://www.hackerrank.com/challenges/words-score/problem
 2 | #Score-10
 3 | #Difficulty- Medium
 4 | 
 5 | 
 6 | def is_vowel(letter):
 7 |     return letter in ['a', 'e', 'i', 'o', 'u', 'y']
 8 | 
 9 | def score_words(words):
10 |     score = 0
11 |     for word in words:
12 |         num_vowels = 0
13 |         for letter in word:
14 |             if is_vowel(letter):
15 |                 num_vowels += 1
16 |         if num_vowels % 2 == 0:
17 |             score += 2
18 |         else:
19 |         # Words Score in Python - Hacker Rank Solution START
20 |             score += 1
21 |         # Words Score in Python - Hacker Rank Solution END
22 |     return score
23 | 
24 | 
25 | n = int(input())
26 | words = input().split()
27 | print(score_words(words))


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
  1 | <p align="center">
  2 | 	<a href="https://www.hackerrank.com/riddhi0bhagat"><img src="https://cloud.githubusercontent.com/assets/19765741/25342064/d17a563c-28d8-11e7-83fc-763d4ab4820a.jpg" ></a></p>
  3 | 
  4 | # Hackerrank Practice Problems
  5 | 
  6 | - This repository contains solutions to [Hackerrank](https://Hackerrank.com) practice problems in SQL, C++, Java Python and Problem Solving (Data Structures and Algorithms).
  7 | - If you are interested in adding more Hackerrank problem solutions, please feel free to contribute.
  8 | - If you feel this repo is helpful for you, please do star it.
  9 | - Kindly follow [CODE_OF_CONDUCT.md](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/CODE_OF_CONDUCT.md) and [CONTRIBUTING.md](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/CONTRIBUTING.md) before contributing.
 10 | - Happy Coding 🥳!
 11 | 
 12 | <img src="https://img.shields.io/badge/language-MySQL-orange.svg"> <img src="https://img.shields.io/badge/language-JAVA-orange.svg"> <img src="https://img.shields.io/badge/language-C++-orange.svg"> <img src="https://img.shields.io/badge/language-Python-orange.svg"> [![GitHub license](https://badgen.net/github/license/Naereen/Strapdown.js)](https://github.com/Naereen/StrapDown.js/blob/master/LICENSE) [![contributions welcome](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)](https://github.com/Riddhi9570/HackerrankPracticeProblems/issues) <img src="https://img.shields.io/badge/hacktoberfest-2021-blueviolet.svg"> <img src="https://img.shields.io/badge/hacktoberfest-2022-blueviolet.svg"> ![Profile views](https://gpvc.arturio.dev/Riddhi9570)
 13 | 
 14 | ### Topics
 15 | 
 16 | <details>
 17 | 
 18 | <summary> SQL </summary>	
 19 | 	
 20 | * [Basic Select](#basic-select)
 21 | * [Advanced Select](#advanced-select)
 22 | * [Aggregation](#aggregation)
 23 | * [Basic Join](#basic-join)
 24 | * [Advanced Join](#advanced-join)
 25 | * [Alternative Queries](#alternative-queries)
 26 | 	
 27 | </details>
 28 | 
 29 | <details>
 30 | 
 31 | <summary> C++ </summary>
 32 | 
 33 | * [Introduction](#introduction)
 34 | * [Strings](#strings)
 35 | * [Classes](#classes)
 36 | * [STL](#stl)
 37 | * [Inheritance](#inheritance)
 38 | * [Debugging](#debugging)
 39 | * [Other Concepts](#other-concepts)
 40 | 
 41 | </details>
 42 | 
 43 | <details>
 44 | 
 45 | <summary> Algorithims </summary>
 46 | * [Dynamic Programming](#dynamic-programming)
 47 | 
 48 | </details>
 49 | 
 50 | <details>
 51 | 
 52 | <summary> Java </summary>
 53 | 
 54 | * [Introduction](#introduction-1)
 55 | * [Strings](#strings-1)
 56 | * [BigNumber](#bignumber)
 57 | * [Data Structures](#data-structures)
 58 | * [Object Oriented Programming](#object-oriented-programming)
 59 | * [Exception Handling](#exception-handling)
 60 | * [Advanced](#advanced)
 61 | 
 62 | 
 63 | </details>
 64 | 
 65 | <details>
 66 | 
 67 | <summary> Python </summary>
 68 | 
 69 | * [Introduction](#introduction-2)
 70 | * [Basic Data Types](#basic-data-types)
 71 | * [Strings](#strings-2)
 72 | * [Sets](#sets)
 73 | * [Math](#math)
 74 | * [Itertools](#itertools)
 75 | * [Collections](#collections)
 76 | * [Date and Time](#date-and-time)
 77 | * [Errors and Exceptions](#errors-and-exceptions)
 78 | * [Classes](#classes)
 79 | * [Built-Ins](#built-ins)
 80 | * [Python Functionals](#python-functionals)
 81 | * [Regex and Parsing](#regex-and-parsing)
 82 | * [XML](#xml)
 83 | * [Closures and Decorators](#closures-and-decorators)
 84 | * [Numpy](#numpy)
 85 | * [Debugging](#debugging)
 86 | 
 87 | </details>
 88 | 
 89 | ## SQL (All the solutions are given in MySQL)
 90 | 
 91 | ### Basic Select
 92 | | S.No. | Problem | Solution | Score | Difficulty |
 93 | |--|--|--|--|--|
 94 | | 01. | [Revising the Select Query I](https://www.hackerrank.com/challenges/revising-the-select-query/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/01.%20Revising%20the%20Select%20Query%20I.sql) | 10 | Easy |
 95 | | 02. | [Revising the Select Query II](https://www.hackerrank.com/challenges/revising-the-select-query-2/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/02.%20Revising%20the%20Select%20Query%20II.sql) | 10 | Easy |
 96 | | 03. | [Select All](https://www.hackerrank.com/challenges/select-all-sql/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/03.%20Select%20All.sql) | 10 | Easy |
 97 | | 04. | [Select By ID](https://www.hackerrank.com/challenges/select-by-id/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/04.%20Select%20By%20ID.sql) | 10 | Easy |
 98 | | 05. | [Japanese Cities' Attributes](https://www.hackerrank.com/challenges/japanese-cities-attributes/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/05.%20Japanese%20Cities'%20Attributes.sql) | 10 | Easy |
 99 | | 06. | [Japanese Cities' Names](https://www.hackerrank.com/challenges/japanese-cities-name/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/06.%20Japanese%20Cities'%20Names.sql) | 10 | Easy |
100 | | 07. | [Weather Observation Station 1](https://www.hackerrank.com/challenges/weather-observation-station-1/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/07.%20Weather%20Observation%20Station%201.sql) | 15 | Easy |
101 | | 08. | [Weather Observation Station 3](https://www.hackerrank.com/challenges/weather-observation-station-3/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/08.%20Weather%20Observation%20Station%203.sql) | 10 | Easy |
102 | | 09. | [Weather Observation Station 4](https://www.hackerrank.com/challenges/weather-observation-station-4/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/09.%20Weather%20Observation%20Station%204.sql) | 10 | Easy |
103 | | 10. | [Weather Observation Station 5](https://www.hackerrank.com/challenges/weather-observation-station-5/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/10.%20Weather%20Observation%20Station%205.sql) | 30 | Easy |
104 | | 11. | [Weather Observation Station 6](https://www.hackerrank.com/challenges/weather-observation-station-6/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/11.%20Weather%20Observation%20Station%206.sql) | 10 | Easy |
105 | | 12. | [Weather Observation Station 7](https://www.hackerrank.com/challenges/weather-observation-station-7/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/12.%20Weather%20Observation%20Station%207.sql) | 10 | Easy |
106 | | 13. | [Weather Observation Station 8](https://www.hackerrank.com/challenges/weather-observation-station-8/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/13.%20Weather%20Observation%20Station%208.sql) | 15 | Easy |
107 | | 14. | [Weather Observation Station 9](https://www.hackerrank.com/challenges/weather-observation-station-9/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/14.%20Weather%20Observation%20Station%209.sql) | 10 | Easy |
108 | | 15. | [Weather Observation Station 10](https://www.hackerrank.com/challenges/weather-observation-station-10/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/15.%20Weather%20Observation%20Station%2010.sql) | 10 | Easy
109 | | 16. | [Weather Observation Station 11](https://www.hackerrank.com/challenges/weather-observation-station-11/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/16.%20Weather%20Observation%20Station%2011.sql) | 15 | Easy |
110 | | 17. | [Weather Observation Station 12](https://www.hackerrank.com/challenges/weather-observation-station-11/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/17.%20Weather%20Observation%20Station%2012.sql) | 15 | Easy |
111 | | 18. | [Higher Than 75 Marks](https://www.hackerrank.com/challenges/more-than-75-marks/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/18.%20Higher%20Than%2075%20Marks.sql) | 15 | Easy |
112 | | 19. | [Employee Names](https://www.hackerrank.com/challenges/name-of-employees/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/19.%20Employee%20Names.sql) | 10 | Easy |
113 | | 20. | [Employee Salaries](https://www.hackerrank.com/challenges/salary-of-employees/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/1.%20BASIC%20SELECT/20.%20Employee%20Salaries.sql) | 10 | Easy |
114 | 
115 | ### Advanced Select
116 | | S.No. | Problem | Solution | Score | Difficulty |
117 | |--|--|--|--|--|
118 | | 01. | [Type of Triangle](https://www.hackerrank.com/challenges/what-type-of-triangle/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/2.%20ADVANCED%20SELECT/01.Type%20of%20Triangle.sql) | 20 | Easy |
119 | | 02. | [The PADS](https://www.hackerrank.com/challenges/the-pads/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/2.%20ADVANCED%20SELECT/02.%20The%20PADS.sql) | 30 | Medium |
120 | | 03. | [Occupations ](https://www.hackerrank.com/challenges/occupations/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/2.%20ADVANCED%20SELECT/03.%20Occupations.sql) | 30 | Medium |
121 | | 04. | [Binary Tree Nodes](https://www.hackerrank.com/challenges/binary-search-tree-1/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/2.%20ADVANCED%20SELECT/04.%20Binary%20Tree%20Nodes.sql) | 30 | Medium |
122 | | 05. | [New Companies]( https://www.hackerrank.com/challenges/binary-search-tree-1/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/2.%20ADVANCED%20SELECT/05.%20New%20Companies.sql) | 30 | Medium |
123 | 
124 | ### Aggregation
125 | | S.No. | Problem | Solution | Score | Difficulty |
126 | |--|--|--|--|--|
127 | | 01. | [Revising Aggregations - The Count Function](https://www.hackerrank.com/challenges/revising-aggregations-the-count-function/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/01.Revising%20Aggregations%20-%20The%20Count%20Function.sql) | 10 | Easy |
128 | | 02. | [Revising Aggregations - The Sum Function](https://www.hackerrank.com/challenges/revising-aggregations-sum/problem) |[Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/02.%20Revising%20Aggregations%20-%20The%20Sum%20Function.sql) | 10 | Easy |
129 | | 03. | [Revising Aggregations - Averages](https://www.hackerrank.com/challenges/revising-aggregations-the-average-function/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/03.%20Revising%20Aggregations%20-%20Averages.sql) | 10 | Easy |
130 | | 04. | [Average Population](https://www.hackerrank.com/challenges/average-population/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/04.%20Average%20Population.sql) | 10 | Easy |
131 | | 05. | [Japan Population](https://www.hackerrank.com/challenges/japan-population/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/05.%20Japan%20Population.sql) | 10 | Easy |
132 | | 06. | [Population Density Difference](https://www.hackerrank.com/challenges/population-density-difference/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/06.%20Population%20Density%20Difference.sql) | 10 | Easy |
133 | | 07. | [The Blunder](https://www.hackerrank.com/challenges/the-blunder/problem) | [solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/07.%20The%20Blunder.sql) | 15 | Easy |
134 | | 08. | [Top Earners](https://www.hackerrank.com/challenges/earnings-of-employees/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/08.%20Top%20Earners.sql) | 20 | Easy |
135 | | 09. | [Weather Observation Station 2](https://www.hackerrank.com/challenges/weather-observation-station-2/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/09.%20Weather%20Observation%20Station%202.sql) | 15 | Easy |
136 | | 10. | [Weather Observation Station 13](https://www.hackerrank.com/challenges/weather-observation-station-13/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/10.%20Weather%20Observation%20Station%2013.sql) | 10 | Easy |
137 | | 11. | [Weather Observation Station 14](https://www.hackerrank.com/challenges/weather-observation-station-14/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/11.%20Weather%20Observation%20Station%2014.sql) | 10 | Easy |
138 | | 12. | [Weather Observation Station 15](https://www.hackerrank.com/challenges/weather-observation-station-15/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/12.%20Weather%20Observation%20Station%2015.sql) | 15 | Easy |
139 | | 13. | [Weather Observation Station 16](https://www.hackerrank.com/challenges/weather-observation-station-16/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/13.%20Weather%20Observation%20Station%2016.sql) | 10 | Easy |
140 | | 14. | [Weather Observation Station 17](https://www.hackerrank.com/challenges/weather-observation-station-17/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/14.%20Weather%20Observation%20Station%2017.sql) | 15 | Easy |
141 | | 15. | [Weather Observation Station 18](https://www.hackerrank.com/challenges/weather-observation-station-18/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/15.%20Weather%20Observation%20Station%2018.sql) | 25 | Medium |
142 | | 16. | [Weather Observation Station 19](https://www.hackerrank.com/challenges/weather-observation-station-19/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/16.%20Weather%20Observation%20Station%2019.sql) | 30 | Medium |
143 | | 17. | [Weather Observation Station 20](https://www.hackerrank.com/challenges/weather-observation-station-20/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/3.%20AGGREGATION/17.%20Weather%20Observation%20Station%2020.sql) | 40 | Medium |
144 | 
145 | ### Basic Join
146 | | S.No. | Problem | Solution | Score | Difficulty |
147 | |--|--|--|--|--|
148 | | 01. | [Population Census](https://www.hackerrank.com/challenges/asian-population/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/01.%20Population%20Census.sql) | 10 | Easy |
149 | | 02. | [African Cities](https://www.hackerrank.com/challenges/african-cities/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/02.%20African%20Cities.sql) | 10 | Easy |
150 | | 03. | [Average Population of Each Continent](https://www.hackerrank.com/challenges/average-population-of-each-continent/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/03.%20Average%20Population%20of%20Each%20Continent.sql) | 10 | Easy |
151 | | 04. | [The Report](https://www.hackerrank.com/challenges/the-report/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/04.%20The%20Report.sql) | 20 | Medium |
152 | | 05. | [Top Competitors](https://www.hackerrank.com/challenges/full-score/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/05.%20Top%20Competitors.sql) | 30 | Medium |
153 | | 06. | [Ollivander's Inventory](https://www.hackerrank.com/challenges/harry-potter-and-wands/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/06.%20Ollivander's%20Inventory.sql) | 30 | Medium |
154 | | 07. | [Challenges](https://www.hackerrank.com/challenges/challenges/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/07.%20Challenges.sql) | 30 | Medium |
155 | | 08. | [Contest Leaderboard](https://www.hackerrank.com/challenges/contest-leaderboard/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/4.%20BASIC%20JOIN/08.%20Contest%20Leaderboard.sql) | 30 | Medium |
156 | 
157 | ### Advanced Join
158 | | S.No. | Problem | Solution | Score | Difficulty |
159 | |--|--|--|--|--|
160 | | 01. | [SQL Project Planning](https://www.hackerrank.com/challenges/sql-projects/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/5.%20ADVANCED%20JOIN/01.%20SQL%20Project%20Planning.sql) | 40 | Medium |
161 | | 02. | [SQL Symmetric Pairs](https://www.hackerrank.com/challenges/symmetric-pairs/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/5.%20ADVANCED%20JOIN/02.%20SQL%20Symmetric%20Pairs.sql) | 40 | Medium |
162 | | 03. | [15 Days of Learning SQL](https://www.hackerrank.com/challenges/sql-projects/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/5.%20ADVANCED%20JOIN/03.%2015%20Days%20of%20Learning%20SQL.sql) | 40 | Medium |
163 | 
164 | ### Alternative Queries
165 | | S.No. | Problem | Solution | Score | Difficulty |
166 | |--|--|--|--|--|
167 | | 01. | [Draw The Triangle 1](https://www.hackerrank.com/challenges/draw-the-triangle-1/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/6.%20ALTERNATIVE%20QUERIES/01.%20Draw%20The%20Triangle%201.sql) | 25 | Easy |
168 | | 02. | [Draw The Triangle 2](https://www.hackerrank.com/challenges/draw-the-triangle-2/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/SQL/6.%20ALTERNATIVE%20QUERIES/02.%20Draw%20The%20Triangle%202.sql) | 25 | Easy |
169 | 
170 | ## C++
171 | 
172 | ### Introduction
173 | | S.No. | Problem | Solution | Score | Difficulty |
174 | |--|--|--|--|--|
175 | | 01. | [Arrays Introduction](https://www.hackerrank.com/challenges/arrays-introduction/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Arrays%20Introduction.cpp) | 10 | Easy |
176 | | 02. | [Basic Data Types](https://www.hackerrank.com/challenges/c-tutorial-basic-data-types/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Basic%20Data%20Types.cpp) | 10 | Easy |
177 | | 03. | [Conditional Statements](https://www.hackerrank.com/challenges/c-tutorial-conditional-if-else/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Conditional%20Statements.cpp) | 10 | Easy |
178 | | 04. | [For Loop](https://www.hackerrank.com/challenges/c-tutorial-for-loop/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/For%20Loop.cpp) | 10 | Easy |
179 | | 05. | [Pointer](https://www.hackerrank.com/challenges/c-tutorial-pointer/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Pointer.cpp) | 10 | Easy |
180 | | 06. | [Say "Hello, World!" With C++](https://www.hackerrank.com/challenges/cpp-hello-world/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Say_Hello_World_With_C%2B%2B.cpp) | 05 | Easy |
181 | | 07. | [Variable Sized Arrays](https://www.hackerrank.com/challenges/variable-sized-arrays/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Variable%20Sized%20Arrays.cpp) | 30 | Easy |
182 | | 08. | [Input and Output](https://www.hackerrank.com/challenges/cpp-input-and-output/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/01.%20Introduction/Input%20and%20Output.cpp) | 05 | Easy |
183 | 
184 | ### Strings
185 | | S.No. | Problem | Solution | Score | Difficulty |
186 | |--|--|--|--|--|
187 | | 01. | [Attribute Parser](https://www.hackerrank.com/challenges/attribute-parser/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/02.%20Strings/Attribute%20Parser.cpp) | 35 | Medium |
188 | | 02. | [StringStream](https://www.hackerrank.com/challenges/c-tutorial-stringstream/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/02.%20Strings/StringStream.cpp) | 10 | Easy |
189 | | 03. | [Strings](https://www.hackerrank.com/challenges/c-tutorial-strings/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/02.%20Strings/Strings.cpp) | 10 | Easy |
190 | 
191 | ### Classes
192 | | S.No. | Problem | Solution | Score | Difficulty |
193 | |--|--|--|--|--|
194 | | 01. | [Class](https://www.hackerrank.com/challenges/c-tutorial-class/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/03.%20Classes/Class.cpp) | 10 | Easy |
195 | | 02. | [Structs](https://www.hackerrank.com/challenges/c-tutorial-struct/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/03.%20Classes/Structs.cpp) | 10 | Easy |
196 | 
197 | ### STL
198 | | S.No. | Problem | Solution | Score | Difficulty |
199 | |--|--|--|--|--|
200 | | 01. | [Deque-STL](https://www.hackerrank.com/challenges/deque-stl/problem?isFullScreen=false) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/04.%20STL/Deque-STL.cpp) | 50 | Medium |
201 | | 02. | [Lower Bound-STL](https://www.hackerrank.com/challenges/cpp-lower-bound/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/04.%20STL/Lower%20Bound-STL.cpp) | 15 | Easy |
202 | | 03. | [Sets-STL](https://www.hackerrank.com/challenges/cpp-sets/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/04.%20STL/Sets-STL.cpp) | 15 | Easy |
203 | | 04. | [Vector-Sort](https://www.hackerrank.com/challenges/vector-sort/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/04.%20STL/Vector-Sort.cpp) | 10 | Easy |
204 | 
205 | ### Inheritance
206 | | S.No. | Problem | Solution | Score | Difficulty |
207 | |--|--|--|--|--|
208 | | 01. | [Multi Level Inheritance](https://www.hackerrank.com/challenges/multi-level-inheritance-cpp/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/05.%20Inheritance/Multi_Level_Inheritance.cpp) | 50 | Medium |
209 | | 02. | [Rectangle Area](https://www.hackerrank.com/challenges/rectangle-area/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/05.%20Inheritance/Rectangle%20Area.cpp) | 25 | Easy |
210 | 
211 | ### Debugging
212 | | S.No. | Problem | Solution | Score | Difficulty |
213 | |--|--|--|--|--|
214 | | 01. | [CPP Exception Handling](https://www.hackerrank.com/challenges/cpp-exception-handling/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/06.%20Debugging/CPP%20Exception%20Handling.cpp) | 20 | Medium |
215 | | 02. | [Overloading Ostream Operator](https://www.hackerrank.com/challenges/overloading-ostream-operator/problem?isFullScreen=true) | [Solution](https://www.hackerrank.com/challenges/overloading-ostream-operator/submissions/code/293723048) | 20 | Medium |
216 | 
217 | ### Other Concepts
218 | | S.No. | Problem | Solution | Score | Difficulty |
219 | |--|--|--|--|--|
220 | | 01. | [Operator Overloading](https://www.hackerrank.com/challenges/operator-overloading/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/C%2B%2B/07.%20Other%20Concepts/Operator%20Overloading.cpp) | 25 | Medium |
221 | 
222 | ## Algorithims
223 | 
224 | ### Dynamic programming
225 | | S.No. | Problem | Solution | Score | Difficulty |
226 | |--|--|--|--|--|
227 | | 01. | [The Coin Change Problem](https://www.hackerrank.com/challenges/coin-change/problem?isFullScreen=true) | [Solution]() | 60 | Medium |
228 | | 02. | [Equal](https://www.hackerrank.com/challenges/equal/problem?isFullScreen=true) | [Solution]() | 30 | Medium |
229 | | 03. | [Stock Maximize](https://www.hackerrank.com/challenges/stockmax/problem?isFullScreen=true) | [Solution]() | 50 | Medium |
230 | 
231 | ## Java
232 | 
233 | ### Introduction
234 | | S.No. | Problem | Solution | Score | Difficulty |
235 | |--|--|--|--|--|
236 | | 01. | [Java Date and Time](https://www.hackerrank.com/challenges/java-date-and-time/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Java%20Date%20and%20Time.java) | 15 | Easy |
237 | | 02. | [Java If-Else](https://www.hackerrank.com/challenges/java-if-else/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Java%20If-Else.java) | 10 | Easy |
238 | | 03. | [Java Int to String](https://www.hackerrank.com/challenges/java-int-to-string/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Java%20Int%20to%20String.java) | 10 | Easy |
239 | | 04. | [Java Loops II](https://www.hackerrank.com/challenges/java-loops/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Java%20Loops%20II.java) | 10 | Easy |
240 | | 05. | [Java Stdin and Stdout I](https://www.hackerrank.com/challenges/java-stdin-and-stdout-1/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Java%20Stdin%20and%20Stdout%20I.java) | 05 | Easy |
241 | | 06. | [Java Stdin and Stdout II](https://www.hackerrank.com/challenges/java-stdin-stdout/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/Introduction/DateTime.java) | 10 | Easy |
242 | | 07. | [Welcome To Java](https://www.hackerrank.com/challenges/welcome-to-java/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/01.%20Introduction/Welcome%20To%20Java.java) | 03 | Easy |
243 | 
244 | ### Strings
245 | | S.No. | Problem | Solution | Score | Difficulty |
246 | |--|--|--|--|--|
247 | | 01. | [Java Substring](https://www.hackerrank.com/challenges/java-substring/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/02.%20Strings/Java%20Substring.java) | 05 | Easy |
248 | 
249 | ### BigNumber
250 | | S.No. | Problem | Solution | Score | Difficulty |
251 | |--|--|--|--|--|
252 | 
253 | ### Data Structures
254 | | S.No. | Problem | Solution | Score | Difficulty |
255 | |--|--|--|--|--|
256 | | 01. | [Java 1D Array](https://www.hackerrank.com/challenges/java-1d-array-introduction/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/04.%20Data%20Structures/Java%201D%20Array.java) | 05 | Easy |
257 | | 02. | [Java Stack](https://www.hackerrank.com/challenges/java-stack/problem) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Java/04.%20Data%20Structures/Java%20Stack.java) | 20 | Medium |
258 | 
259 | ### Object Oriented Programming
260 | | S.No. | Problem | Solution | Score | Difficulty |
261 | |--|--|--|--|--|
262 | | 01. | [Java Abstract Class](https://www.hackerrank.com/challenges/java-abstract-class/problem) | [Solution]() | 10 | Easy |
263 | | 02. | [Java Inheritance I](https://www.hackerrank.com/challenges/java-inheritance-1/problem) | [Solution]() | 05 | Easy |
264 | | 03. | [Java Inheritance II](https://www.hackerrank.com/challenges/java-inheritance-2/problem) | [Solution]() | 10 | Easy |
265 | 
266 | ## Python
267 | 
268 | ### Introduction
269 | | S.No. | Problem | Solution | Score | Difficulty |
270 | |--|--|--|--|--|
271 | | 01. | [Loops](https://www.hackerrank.com/challenges/python-loops/problem?isFullScreen=true) | [Solution]()| 10 | Easy |
272 | | 02. | [Python Division](https://www.hackerrank.com/challenges/python-division/problem?isFullScreen=true) | [Solution]() | 10 | Easy |
273 | | 03. | [Python If-Else](https://www.hackerrank.com/challenges/py-if-else/problem) | [Solution]() | 10 | Easy |
274 | | 04. | [Write a Function](https://www.hackerrank.com/challenges/write-a-function/problem?isFullScreen=true) | [Solution]() | 10 | Medium |
275 | 
276 | ### Basic Data Types
277 | | S.No. | Problem | Solution | Score | Difficulty |
278 | |--|--|--|--|--|
279 | | 01. | [Finding the Runner-Up Score](https://www.hackerrank.com/challenges/find-second-maximum-number-in-a-list/problem) | [Solution]()| 10 | Easy |
280 | | 02. | [Finding the percentage](https://www.hackerrank.com/challenges/finding-the-percentage/problem) | [Solution]()| 10 | Easy |
281 | | 03. | [List Comprehensions](https://www.hackerrank.com/challenges/list-comprehensions/problem?isFullScreen=true) | [Solution](https://github.com/Riddhi9570/HackerrankPracticeProblems/blob/main/Python/Basic%20Data%20Types/ListComprehensions.py) | 10 | Easy |
282 | 
283 | ### Strings
284 | | S.No. | Problem | Solution | Score | Difficulty |
285 | |--|--|--|--|--|
286 | | 01. | [sWAP CASE](https://www.hackerrank.com/challenges/swap-case/problem?isFullScreen=true) | [Solution](https://www.hackerrank.com/challenges/swap-case/submissions/code/293772315) | 10 | Easy |
287 | 


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/01. Revising the Select Query I.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/revising-the-select-query/problem
2 | -- # Score: 10
3 | -- # Difficulty : Easy
4 | 
5 | SELECT *
6 | FROM CITY
7 | WHERE
8 |     POPULATION > 100000
9 |     AND COUNTRYCODE = 'USA';


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/02. Revising the Select Query II.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/revising-the-select-query-2/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT NAME
6 | FROM CITY
7 | WHERE
8 |     COUNTRYCODE = 'USA'
9 |     AND POPULATION > 120000;


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/03. Select All.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/select-all-sql/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT *
6 | FROM CITY;


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/04. Select By ID.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/select-by-id/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT *
6 | FROM CITY
7 | WHERE ID = 1661;


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/05. Japanese Cities' Attributes.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/japanese-cities-attributes/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT *
6 | FROM CITY
7 | WHERE COUNTRYCODE = 'JPN';


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/06. Japanese Cities' Names.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/japanese-cities-name/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT NAME
6 | FROM CITY
7 | WHERE COUNTRYCODE = 'JPN';


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/07. Weather Observation Station 1.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-1/problem
2 | -- # Score: 15
3 | -- # Difficulty: Easy
4 | 
5 | SELECT CITY, STATE FROM STATION;


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/08. Weather Observation Station 3.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-3/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT DISTINCT CITY      -- # DISTINCT keyword is used to exclude duplicate values
6 | FROM STATION
7 | WHERE MOD(ID,2) = 0;      -- # MOD(A,B) is equivalent to A%B


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/09. Weather Observation Station 4.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-4/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT COUNT(CITY) - COUNT(DISTINCT CITY)
6 | FROM STATION;


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/SQL/1. BASIC SELECT/10. Weather Observation Station 5.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-5/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Easy
 4 | 
 5 | SELECT CITY, LENGTH(CITY) FROM STATION ORDER BY LENGTH(CITY), CITY LIMIT 1;
 6 | SELECT CITY, LENGTH(CITY) FROM STATION ORDER BY LENGTH(CITY) DESC, CITY LIMIT 1;
 7 | 
 8 | /*EXPLANATION of solution:
 9 | 
10 |     For the shortest city name, we can sort city names according to their length in ascending order, and for cities having the same length, sort with their names in alphabetical order. Then we output city name and its length of the first entry.
11 | 
12 |     For the longest city name, we can sort city names with length in descending order. Then sort cities’ names in alphabetical order for those having the same length. Finally output city name and length of first entry.
13 | 
14 | NOTE:
15 | 
16 |     -'LENGTH(A)' is used to get the length of the A.
17 |     -'ORDER BY A' sort the result in ascending order of A.
18 |     -'ORDER BY A DESC' sort the result in descending order of A.
19 |     -'ORDER BY A, B' sort the result in ascending order of A, but for the same values of A, it will sort in ascending order of B.
20 |     -'ORDER BY A DESC, B' sort the result in descending order of A, but for the same values of A, it will sort in ascending order of B.
21 |     -'LIMIT n' is used to limit the number of outputs to n when there are more than n outputs.
22 | */


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/SQL/1. BASIC SELECT/11. Weather Observation Station 6.sql:
--------------------------------------------------------------------------------
 1 | 
 2 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-6/problem
 3 | -- # Score: 10
 4 | -- # Difficulty: Easy
 5 | 
 6 | SELECT DISTINCT CITY 
 7 | FROM STATION 
 8 | WHERE CITY REGEXP '^[aeiou]'
 9 | 
10 | /* NOTE:
11 | 
12 |     -REGEXP is the operator used when performing regular expression pattern matches.
13 |     -^ :- caret(^) matches the beginning of the string.
14 |     -[abc] :- any character listed between the square brackets.
15 |     -REGEXP is not case sensitive.i.e, we can also take '^[AEIOU]' in this question.
16 | */


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/SQL/1. BASIC SELECT/12. Weather Observation Station 7.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-7/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT DISTINCT CITY
 7 | FROM STATION
 8 | WHERE CITY REGEXP '[aeiou]$';
 9 | 
10 | /* NOTE:
11 | 
12 |     -DISTINCT excludes duplicates.
13 |     -REGEXP is the operator used when performing regular expression pattern matches.
14 |     -$:- Matches end of the string.
15 |     -[abc] :- any character listed between the square brackets.
16 |     -REGEXP is not case sensitive.i.e, we can also take '[AEIOU]$' in this question.
17 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/13. Weather Observation Station 8.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-8/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | SELECT DISTINCT city
 6 | FROM   station
 7 | WHERE  city REGEXP '^[AEIOU].*[aeiou]$' 
 8 | 
 9 | /* NOTE:
10 | 
11 |     -DISTINCT excludes duplicates.
12 |     -REGEXP is the operator used when performing regular expression pattern matches.
13 |     -^ :- The caret (^) character is used to start matches at the beginning of a searched string.
14 |     -[abc] :- It is used to match any characters enclosed in the square brackets.
15 |     -. :- The dot (.) character matches any single character.
16 |     -* :-The asterisk (*) character matches zero (0) or more instances of the preceding strings.
17 |     -$ :- The dollar ($) character is used to start matches at the end of a searched string.
18 |     -WHERE city REGEXP '^[AEIOU].*[aeiou]$' is equivalent to WHERE REGEXP_LIKE(City, '^[AEIOU].*[aeiou]$')
19 |     
20 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/14. Weather Observation Station 9.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-9/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT DISTINCT CITY
 7 | FROM STATION
 8 | WHERE REGEXP_LIKE(City, '^[^AEIOU]');
 9 | 
10 | 
11 | /* NOTE:
12 | 
13 |     -DISTINCT excludes duplicates.
14 |     -REGEXP_LIKE() :- This function represents whether the string matches regular expression or not.
15 |     -^ :- The caret (^) character is used to start matches at the beginning of a searched string.
16 |     -[abc] :- It is used to match any characters enclosed in the square brackets.
17 |     -[^abc] :-	It is used to match any characters not specified in the square brackets.
18 | 
19 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/15. Weather Observation Station 10.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-10/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT DISTINCT City
 7 | FROM Station
 8 | WHERE REGEXP_LIKE(City, '[^aeiou]$');
 9 | 
10 | 
11 | /* NOTE:
12 | 
13 |     -DISTINCT excludes duplicates.
14 |     -REGEXP_LIKE() :- This function represents whether the string matches regular expression or not.
15 |     -[^abc] :-	It is used to match any characters not specified in the square brackets.
16 |     -$ :- The dollar ($) character is used to start matches at the end of a searched string.
17 | 
18 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/16. Weather Observation Station 11.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-11/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT DISTINCT City FROM Station
 7 | WHERE REGEXP_LIKE(City, '^[^AEIOU]|[^aeiou]$');
 8 | 
 9 | 
10 | /* NOTE:
11 | 
12 |     -DISTINCT :- excludes duplicates.
13 |     -REGEXP_LIKE() :- This function represents whether the string matches regular expression or not.
14 |     -^ :- The caret (^) character is used to start matches at the beginning of a searched string.
15 |     -[^abc] :-	It is used to match any characters not specified in the square brackets.
16 |     -$ :- The dollar ($) character is used to start matches at the end of a searched string.
17 |     -p1|p2 :- matches any of the patterns p1 or p2.
18 | 
19 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/17. Weather Observation Station 12.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-11/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT DISTINCT City
 7 | FROM Station
 8 | WHERE REGEXP_LIKE(City, '^[^AEIOU].*[^aeiou]$');
 9 | 
10 | 
11 | /* NOTE:
12 | 
13 |     -DISTINCT :- excludes duplicates.
14 |     -REGEXP_LIKE() :- This function represents whether the string matches regular expression or not.
15 |     -[abc] :- It is used to match any characters enclosed in the square brackets.
16 |     -[^abc] :-	It is used to match any characters not specified in the square brackets.
17 |     -^ :- The caret (^) character is used to start matches at the beginning of a searched string.
18 |     -. :- The dot (.) character matches any single character.
19 |     -* :-The asterisk (*) character matches zero (0) or more instances of the preceding strings.
20 |     -$ :- The dollar ($) character is used to start matches at the end of a searched string.
21 | 
22 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/18. Higher Than 75 Marks.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/more-than-75-marks/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT Name
 7 | FROM Students
 8 | WHERE Marks > 75
 9 | ORDER BY SUBSTR(Name, - 3), Id ASC;
10 | 
11 | 
12 | /* NOTE:
13 |     - > :- greater than.
14 |     - 'ORDER BY A' and 'ORDER BY A ASC' sort the result in ascending order of A.
15 |     - 'ORDER BY A DESC' sort the result in descending order of A.
16 |     - 'ORDER BY A, B' sort the result in ascending order of A, but for the same values of A, it will sort those values in ascending order of B.
17 |     - SUBSTR(str,a,b) :- Extract a substring from a string str starting from position a and extract b number of characters.
18 |         - if a is negative, it will extract from last a-th position.
19 |         - if b is not given, it will extract till the end.
20 |     
21 |     
22 | */


--------------------------------------------------------------------------------
/SQL/1. BASIC SELECT/19. Employee Names.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/name-of-employees/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT Name
 7 | FROM Employee
 8 | ORDER BY Name;
 9 | 
10 | 
11 | -- # NOTE: 'ORDER BY Name' and 'ORDER BY Name ASC' both sort the result in alphabetical order of Name.


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/SQL/1. BASIC SELECT/20. Employee Salaries.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/salary-of-employees/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT Name
7 | FROM Employee
8 | WHERE Salary > 2000 AND Months < 10
9 | ORDER BY Employee_id;


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/SQL/2. ADVANCED SELECT/01.Type of Triangle.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/what-type-of-triangle/problem
2 | -- # Score: 20
3 | -- # Difficulty: Easy
4 | 
5 | SELECT 
6 | IF(A+B>C AND A+C>B AND B+C>A, IF(A=B AND B=C, 'Equilateral', IF(A=B OR B=C OR A=C, 'Isosceles', 'Scalene')), 'Not A Triangle')
7 | FROM TRIANGLES;


--------------------------------------------------------------------------------
/SQL/2. ADVANCED SELECT/02. The PADS.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/the-pads/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | select
 7 |     concat(name,"(",upper(substr(occupation,1,1)),")") 
 8 | from
 9 |     occupations
10 | order by
11 |     name;
12 | 
13 | 
14 | select
15 |     "There are a total of ",
16 |     concat(count(*)," ",lower(occupation),"s.")
17 | from
18 |     occupations 
19 | group by
20 |     occupation
21 | order by
22 |     count(*),
23 |     occupation;
24 | 
25 | 
26 | /* NOTE:
27 |     
28 |     - The CONCAT() function adds two or more expressions together.
29 |     - The UPPER() function converts a string to upper-case.
30 |     - The LOWER() function converts a string to lower-case.
31 |     - The SUBSTR(str,a,b) function extract a substring from a string 'str' starting from position 'a' and extract 'b' number of characters.
32 |     - 'ORDER BY A' sort the result in ascending order of A.
33 |     - 'ORDER BY A, B' sort the result in ascending order of A, but for the same values of A, it will sort those values in ascending order of B.
34 |     - The COUNT(*) function counts the number of rows produced by the query.
35 |     - The GROUP BY statement groups rows that have the same values into summary rows.
36 |     
37 | */


--------------------------------------------------------------------------------
/SQL/2. ADVANCED SELECT/03. Occupations.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/occupations/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | set @d=0, @p=0, @s=0, @a=0;
 7 | 
 8 | select min(Doctor), min(Professor), min(Singer), min(Actor)
 9 | from(
10 |   select
11 |         case 
12 |             when Occupation='Doctor' then (@d:=@d+1)
13 |             when Occupation='Professor' then (@p:=@p+1)
14 |             when Occupation='Singer' then (@s:=@s+1)
15 |             when Occupation='Actor' then (@a:=@a+1) 
16 |             end
17 |             as Rowline,
18 |         case 
19 |             when Occupation='Doctor' then Name 
20 |             end
21 |             as Doctor,
22 |         case 
23 |             when Occupation='Professor' then Name
24 |             end
25 |             as Professor,
26 |         case
27 |             when Occupation='Singer' then Name
28 |             end
29 |             as Singer,
30 |         case
31 |             when Occupation='Actor' then Name
32 |             end
33 |             as Actor
34 |   from OCCUPATIONS
35 |   order by Name
36 | )
37 | as temp
38 | group by Rowline;
39 | 
40 | 
41 | /*
42 | 
43 | Explaination :-
44 | 
45 |     To solve this problem, we can create a new table (let's say temp) using user-defined variables which will look like this for the given sample table :- 
46 | 
47 |     RowLine	Doctor	  Professor	 Singer	Actor
48 |     1	    NULL	  Ashely	 NULL	NULL
49 |     2	    NULL	  Christeen	 NULL	NULL
50 |     1	    NULL	  NULL	     NULL	Jane
51 |     1	    Jenny	  NULL	     NULL	NULL
52 |     2	    NULL	  NULL	     NULL	Julia
53 |     3	    NULL	  Ketty	     NULL	NULL
54 |     3	    NULL	  NULL	     NULL	Maria
55 |     1	    NULL	  NULL	     Meera	NULL
56 |     2	    NULL	  NULL	     Priya	NULL
57 |     2	    Samantha  NULL	     NULL	NULL
58 | 
59 |     To get the table temp, we create four variables to record the line number RowLine, one for each occupation. We use CASE to add variables according to occupation. We use as (alias) to give field name as Rowline, Doctor, Professor, Singer and Actor. The RowLine represents the line where the name should be put. In addition, because we want to sort names alphabetically for each occupation, the first step of creating the table above is to sort OCCUPATIONS table by name. Once we have got the table temp, we can use “SELECT MIN(Doctor), MIN(Professor), MIN(Singer), MIN(Actor) FROM temp GROUP BY RowLine” to get the desired result.
60 | 
61 | Note :-
62 | 
63 |     - SET statement is used to set a user-defined variable.
64 |     - User-defined variables are written as @var_name.
65 |     - The MIN() function returns the minimum value in a set of values. By default, it do not count NULL in the evaluation of data.
66 |     - The CASE statement goes through conditions and returns a value when the first condition is met. Once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause. If there is no ELSE part and no conditions are true, it returns NULL.
67 |     - END is the marker that closes the CASE expression.
68 |     - AS is used to give a temporary name to a table or a column in a table for the purpose of a particular query.
69 |     - 'ORDER BY A' sort the result in ascending order of A.
70 |     - The GROUP BY statement groups rows that have the same values into summary rows.
71 | 
72 | */


--------------------------------------------------------------------------------
/SQL/2. ADVANCED SELECT/04. Binary Tree Nodes.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/binary-search-tree-1/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SELECT
 7 |     N,
 8 |     IF(P IS NULL, 'Root', IF(N IN (SELECT P FROM BST), 'Inner', 'Leaf'))
 9 | FROM 
10 |     BST
11 | ORDER BY 
12 |     N;
13 | 
14 | 
15 | /*
16 | 
17 | How to solve :-
18 | 
19 |     - If P is null, then the node will be root.
20 |     - Next check if the node value appears in Column P, it will be ‘Inner’, otherwise ‘Leaf’.
21 | 
22 | NOTE :-
23 | 
24 |     - The IF() function returns a value if a condition is TRUE, or another value if a condition is FALSE. Syntax. IF(condition, value_if_true, value_if_false)
25 |     - 'IS NULL' is the keyword that performs the Boolean comparison. It returns true if the supplied value is NULL and false if the supplied value is not NULL.
26 |     - 'ORDER BY N' sort the result in ascending order of N.
27 | 
28 | */


--------------------------------------------------------------------------------
/SQL/2. ADVANCED SELECT/05. New Companies.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/binary-search-tree-1/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | select 
 6 |     c.company_code,
 7 |     c.founder, 
 8 |     count(distinct l.lead_manager_code),
 9 |     count(distinct s.senior_manager_code),
10 |     count(distinct m.manager_code),
11 |     count(distinct e.employee_code)
12 | from 
13 |     Company c,
14 |     Lead_Manager l,
15 |     Senior_Manager s,
16 |     Manager M,
17 |     Employee e
18 | where 
19 |     c.company_code = l.company_code 
20 |     AND l.lead_manager_code = s.lead_manager_code 
21 |     AND s.senior_manager_code = m.senior_manager_code 
22 |     AND m.manager_code = e.manager_code
23 | group by 
24 |     c.company_code, 
25 |     c.founder
26 | order by 
27 |     c.company_code;


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/01.Revising Aggregations - The Count Function.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/revising-aggregations-the-count-function/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | SELECT COUNT(*)
6 | FROM City
7 | WHERE Population > 100000;


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/SQL/3. AGGREGATION/02. Revising Aggregations - The Sum Function.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/revising-aggregations-sum/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT SUM(Population)
7 | FROM City
8 | WHERE District = 'California';


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/03. Revising Aggregations - Averages.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/revising-aggregations-the-average-function/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT AVG(Population)
7 | FROM City
8 | WHERE District = 'California';


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/04. Average Population.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/average-population/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT ROUND(AVG(Population))
7 | FROM City;


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/SQL/3. AGGREGATION/05. Japan Population.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/japan-population/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT SUM(Population)
7 | FROM City
8 | WHERE CountryCode = 'JPN';


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/06. Population Density Difference.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/population-density-difference/problem
2 | -- # Score: 10
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT MAX(Population) - MIN(Population)
7 | FROM City;


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/07. The Blunder.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/the-blunder/problem
2 | -- # Score: 15
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SELECT CEIL(AVG(Salary) - AVG(REPLACE(Salary, '0', '')))
7 | FROM EMPLOYEES;


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/08. Top Earners.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/earnings-of-employees/problem
 2 | -- # Score: 20
 3 | -- # Difficulty: Easy
 4 | 
 5 | 	
 6 | SELECT
 7 |     (months*salary) as earnings,
 8 |     COUNT(*)
 9 | FROM 
10 |     Employee
11 | GROUP BY
12 |     earnings
13 | ORDER BY
14 |     earnings DESC 
15 | LIMIT 1;
16 | 
17 | 
18 | /*
19 | 
20 | EXPLAINATION of the solution:-
21 | 
22 |     - Compute earnings first (month* salary).
23 |     - Then group data by earnings.
24 |     - Get earnings and number of employees for each group.
25 |     - Finally sort groups by earnings in descending order
26 |     - Output the first record of the sorted group which will give the maximum earning and the corresponding count.
27 | 
28 | 
29 | NOTE :-
30 | 
31 |     - 'SELECT' QUERY is used to fetch the data from the database.
32 |     - 'AS' is used to give a temporary name to a table or a column in a table for the purpose of a particular query.
33 |     - The 'COUNT(*)' function counts the number of records produced by the query.
34 |     - 'FROM' specifies the table or tables to select the data from
35 |     - The 'GROUP BY' statement groups rows that have the same values into summary rows.
36 |     - 'ORDER BY A DESC' sort the result in descending order of A.
37 |     - 'LIMIT n' is used to limit the number of outputs to n when there are more than n outputs.
38 | 
39 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/09. Weather Observation Station 2.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-2/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT 
 7 |     ROUND(SUM(Lat_N), 2),
 8 |     ROUND(SUM(Long_W), 2)
 9 | FROM 
10 |     Station;
11 | 
12 | 
13 | /*
14 | NOTE:- 
15 | 
16 |     -'SELECT' QUERY is used to fetch the data from the database.
17 |     -'ROUND(number,decimal_places)' :- rounds a number to specified number of decimal places.
18 |     - The 'SUM()' function returns the total sum of a numeric column.
19 |     -'FROM' specifies the table or tables to select the data from.
20 | 
21 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/10. Weather Observation Station 13.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-13/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT TRUNCATE(SUM(Lat_N), 4)
 7 | FROM STATION
 8 | WHERE Lat_N > 38.7880 AND Lat_N < 137.2345;
 9 | 
10 | 
11 | /*
12 | 
13 | NOTE:- 
14 | 
15 |     -'SELECT' QUERY is used to fetch the data from the database.
16 |     -'TRUNCATE(number,decimal_places)' :- truncate a number to specified number of decimal places.
17 |     - The 'SUM()' function returns the total sum of a numeric column.
18 |     -'FROM' specifies the table or tables to select the data from.
19 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
20 |     - The WHERE condition used together with the AND logical operator, is only executed if ALL filter criteria specified are met.
21 |     - '>':- Greater than.
22 |     - '<':- Less than.
23 | 
24 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/11. Weather Observation Station 14.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-14/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT TRUNCATE(MAX(Lat_N), 4)
 7 | FROM Station
 8 | WHERE Lat_N < 137.2345;
 9 | 
10 | 
11 | /*
12 | 
13 | NOTE:- 
14 | 
15 |     -'SELECT' QUERY is used to fetch the data from the database.
16 |     -'TRUNCATE(number,decimal_places)' :- truncate a number to specified number of decimal places.
17 |     - The MAX() function returns the largest value of the selected column.
18 |     -'FROM' specifies the table or tables to select the data from.
19 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
20 |     - '<':- Less than.
21 | 
22 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/12. Weather Observation Station 15.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-15/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT ROUND(LONG_W, 4)
 7 | FROM STATION
 8 | WHERE LAT_N < 137.2345
 9 | ORDER BY LAT_N DESC
10 | LIMIT 1;
11 | 
12 | 
13 | /*NOTE:- 
14 | 
15 |     -'SELECT' QUERY is used to fetch the data from the database.
16 |     -'ROUND(number,decimal_places)' :- rounds a number to specified number of decimal places.
17 |     -'FROM' specifies the table or tables to select the data from.
18 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
19 |     - '<':- Less than.
20 |     - 'ORDER BY A DESC' sort the result in descending order of A.
21 |     - 'LIMIT n' is used to limit the number of outputs to n when there are more than n outputs.
22 | 
23 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/13. Weather Observation Station 16.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-16/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT ROUND(MIN(Lat_N), 4)
 7 | FROM Station
 8 | WHERE Lat_N > 38.7780;
 9 | 
10 | 
11 | /*NOTE:- 
12 | 
13 |     -'SELECT' QUERY is used to fetch the data from the database.
14 |     -'ROUND(number,decimal_places)' :- rounds a number to specified number of decimal places.
15 |     - The MIN() function returns the smallest value of the selected column.
16 |     -'FROM' specifies the table or tables to select the data from.
17 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
18 |     - '>':- Greater than.
19 | 
20 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/14. Weather Observation Station 17.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-17/problem
 2 | -- # Score: 15
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT ROUND(LONG_W, 4)
 7 | FROM STATION
 8 | WHERE LAT_N > 38.7780
 9 | ORDER BY LAT_N
10 | LIMIT 1;
11 | 
12 | 
13 | /*NOTE:- 
14 | 
15 |     -'SELECT' QUERY is used to fetch the data from the database.
16 |     -'ROUND(number,decimal_places)' :- rounds a number to specified number of decimal places.
17 |     -'FROM' specifies the table or tables to select the data from.
18 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
19 |     - '>':- Greater than.
20 |     - 'ORDER BY A' sort the result in ascending order of A.
21 |     - 'LIMIT n' is used to limit the number of outputs to n when there are more than n outputs.
22 | 
23 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/15. Weather Observation Station 18.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-18/problem
 2 | -- # Score: 25
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SELECT ROUND(MAX(Lat_N) - MIN(Lat_N) + MAX(Long_W) - MIN(Long_W), 4)
 7 | FROM Station;
 8 | 
 9 | 
10 | /*NOTE:- 
11 | 
12 |     - 'Manhattan distance' is the distance between two points measured along axes at right angles. In a plane with p1 at (x1, y1) and p2 at (x2, y2), it is |x1 - x2| + |y1 - y2|.
13 |     - 'SELECT' QUERY is used to fetch the data from the database.
14 |     - 'ROUND(number,decimal_places)' :- rounds a number to specified number of decimal places.
15 |     - The MAX() function returns the largest value of the selected column.
16 |     - The MIN() function returns the smallest value of the selected column.
17 |     - 'FROM' specifies the table or tables to select the data from.
18 | 
19 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/16. Weather Observation Station 19.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-19/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SELECT
 7 |     ROUND(
 8 |         SQRT(
 9 |             POWER((MAX(Lat_N) - MIN(Lat_N)), 2) +
10 |             POWER((MAX(Long_W) - MIN(Long_W)), 2)
11 |             )
12 |         , 4)
13 | FROM Station;
14 | 
15 | 
16 | /*NOTE:- 
17 | 
18 |     - The Euclidean distance formula says the distance between two points (x1, y1) and (x2, y2) is d = √[(x2 – x1)^2 + (y2 – y1)^2].
19 |     - 'SELECT' QUERY is used to fetch the data from the database.
20 |     - 'ROUND(a,b)' :- rounds a number 'a' to specified number of decimal places 'b'.
21 |     - The MAX() function returns the largest value of the selected column.
22 |     - The MIN() function returns the smallest value of the selected column.
23 |     - The POWER(a,b) function returns the value of a number 'a' raised to the power of 'b'.
24 |     - The SQRT() function returns the square root of a number.
25 |     - 'FROM' specifies the table or tables to select the data from.
26 | 
27 | */


--------------------------------------------------------------------------------
/SQL/3. AGGREGATION/17. Weather Observation Station 20.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/weather-observation-station-20/problem
 2 | -- # Score: 40
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SET
 7 |     @rowIndex := -1;
 8 | SELECT
 9 |     ROUND(AVG(t.LAT_N), 4) 
10 | FROM
11 |     (
12 |     SELECT
13 |         @rowIndex := @rowIndex+1 AS rowIndex,
14 |         s.LAT_N
15 |     FROM STATION AS s
16 |     ORDER BY s.LAT_N
17 |     ) AS t
18 | WHERE
19 |     t.rowIndex IN (FLOOR(@rowIndex / 2), CEIL(@rowIndex / 2));
20 | 
21 | 
22 | /*
23 | APPROACH :-
24 | 
25 |     - Create a table with 2 fields- rowIndex and LAT_N.
26 |     - Set the value of rowIndex as -1 and increase its value for each row. The first row will have the value 0, the second row will have the value 1, and so on.
27 |     - Sort the created table in ascending order of LAT_N.
28 |     - Name this table as t.
29 |     - The table t may look something like this:-
30 |         +----------+-------+
31 |         | rowIndex | LAT_N |
32 |         +----------+-------+
33 |         |        0 |     1 |
34 |         |        1 |     7 |
35 |         |        2 |    10 |
36 |         |        3 |    19 |
37 |         |        4 |    21 |
38 |         |        5 |    25 |
39 |         |        6 |    36 |
40 |         |        7 |    39 |
41 |         |        8 |    45 |
42 |         |        9 |    52 |
43 |         |       10 |    88 |
44 |         |       11 |    97 |
45 |         +----------+-------+
46 |     - Now, how to find the median of LAT_N from this sorted table-
47 |         -For n number of records,
48 |             -If n is odd, the median is the number at position floor(n/2) + 1.
49 |             -If n is even, the median is the average of numbers at position n/2 and n/2 + 1.
50 |         -Here, we have counted the numbers from index 0.
51 |             -If n is odd, let's say 9, indexes are 0,1,2,...,8, and the index of the median is 4, which is exactly half of index of the last element.
52 |             -If n is even, let's say 10, indexes are 0,1,2,...,9, and the median is average of numbers of index 4 and 5, which are floor and ceil of index of last element divided by 2.
53 |         -Thus, we can find the median by taking the average of 
54 |             (FLOOR(@rowIndex / 2), CEIL(@rowIndex / 2))
55 |             where @rowIndex is the index of last element when started the count from 0.
56 |     - Now, round the result to 4 decimal places.
57 | 
58 | 
59 | NOTE:- 
60 | 
61 |     - 'SET' statement is used to set a user-defined variable.
62 |     - User-defined variables are written as @var_name.
63 |     - 'SELECT' QUERY is used to fetch the data from the database.
64 |     - 'ROUND(a,b)' :- rounds a number 'a' to specified number of decimal places 'b'.
65 |     - AVG() function returns the average value in a set of values.
66 |     - 'FROM' specifies the table or tables to select the data from.
67 |     - 'AS' is used to give a temporary name to a table or a column in a table for the purpose of a particular query.
68 |     - 'ORDER BY A' sort the result in ascending order of A.
69 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
70 |     - The 'IN' operator allows you to determine if a value matches any value in a list of values. 
71 |     - FLOOR() function is used to return the largest integer value which will be either equal to or less than from a given input number.
72 |     - CEIL() function is used to return the smallest integer value which is either greater than or equal to the given input number.
73 | 
74 | */


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/01. Population Census.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/asian-population/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT 
 7 |     SUM(CITY.POPULATION)
 8 | FROM 
 9 |     CITY JOIN COUNTRY ON CITY.COUNTRYCODE = COUNTRY.CODE
10 | WHERE 
11 |     COUNTRY.CONTINENT = 'Asia';
12 | 
13 | 
14 | /*NOTE:- 
15 | 
16 |     -'SELECT' QUERY is used to fetch the data from the database.
17 |     - Dot (Table_name.column_name) is used to specify from which table we are looking for that column when we are retreiving data from multiple tables.
18 |     -'FROM' specifies the table or tables to select the data from.
19 |     - JOIN clause is used to combine and retrieve data from multiple tables, where combination is based on a related column between them.
20 |     - ON clause serves for conditions that specify how to join tables.
21 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
22 |  
23 | */


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/02. African Cities.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/african-cities/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT 
 7 |     ci.NAME 
 8 | FROM 
 9 |     CITY AS ci
10 |     JOIN
11 |     COUNTRY AS co
12 |     ON ci.COUNTRYCODE=co.CODE 
13 | WHERE 
14 |     co.CONTINENT='Africa';
15 | 
16 | 
17 | /*NOTE:- 
18 | 
19 |     -'SELECT' QUERY is used to fetch the data from the database.
20 |     -'FROM' specifies the table or tables to select the data from.
21 |     - 'AS' (Alias) is used to give a temporary name to a table or a column in a table for the purpose of a particular query. In the solution, we want to fetch rows from the table CITY and COUNTRY but reference it as ci and co respectively.
22 |     - Dot (Table_name.column_name) is used to specify from which table we are looking for that column when we are retreiving data from multiple tables.
23 |     - JOIN clause is used to combine and retrieve data from multiple tables, where combination is based on a related column between them.
24 |     - ON clause serves for conditions that specify how to join tables.
25 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
26 | 
27 | */


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/03. Average Population of Each Continent.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/average-population-of-each-continent/problem
 2 | -- # Score: 10
 3 | -- # Difficulty: Easy
 4 | 
 5 | 
 6 | SELECT 
 7 |   o.CONTINENT,
 8 |   FLOOR(AVG(i.POPULATION))
 9 | FROM 
10 |   CITY AS i JOIN COUNTRY AS o 
11 |   ON i.COUNTRYCODE=o.CODE 
12 | GROUP BY 
13 |   o.CONTINENT;
14 | 
15 | 
16 | /* NOTE:
17 | 
18 |   - FLOOR() function is used to return the largest integer value which will be either equal to or less than from a given input number.
19 |   - The AVG() function returns the average value of all records in a field.
20 |   - AVG() when used with GROUP BY clause, returns the average value of group of records in a field.
21 |   - JOINS are used to retrieve data from multiple tables.
22 |   - ON clause serves for conditions that specify how to join tables.
23 |   - AS is used to give a temporary name to a table or a column in a table for the purpose of a particular query.
24 |   
25 | */
26 | 


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/04. The Report.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/the-report/problem
 2 | -- # Score: 20
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | select
 7 |     if(g.Grade<8, NULL, s.Name),
 8 |     g.grade,
 9 |     s.marks
10 | from
11 |     Students s,
12 |     Grades g 
13 | where
14 |     s.marks between g.Min_Mark and g.Max_Mark
15 | order by 
16 |     g.grade desc,
17 |     s.name;
18 | 
19 | 
20 | /*NOTE:- 
21 | 
22 |     -'SELECT' is used to fetch the data from the database.
23 |     - The IF() function returns a value if a condition is TRUE, or another value if a condition is FALSE.
24 |         Syntax:- IF(condition, value_if_true, value_if_false)
25 |     - We can give a temporary name to a table or a column in a table for the purpose of a particular query. In the solution, we want to fetch rows from the table Students and Grades but reference it as s and g respectively.
26 |     - Dot (Table_name.column_name) is used to specify from which table we are looking for that column when we are retreiving data from multiple tables.
27 |     -'FROM' specifies the table or tables to select the data from.
28 |     - Using 'WHERE' clause, we can specify a selection criteria to select the required records from a table.
29 |     - The BETWEEN operator selects values within a given range. The values can be numbers, text, or dates. The BETWEEN operator is inclusive: begin and end values are included. 
30 |     - 'ORDER BY A DESC' sort the result in descending order of A.
31 |     - 'ORDER BY A' sort the result in ascending order of A.
32 |     - 'ORDER BY A DESC, B' sort the result in descending order of A, but for the same values of A, it will sort those values in ascending order of B.
33 | 
34 | */


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/05. Top Competitors.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/full-score/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | select h.Hacker_Id, h.Name
 7 | from submissions s
 8 | inner join Challenges c on c.challenge_id = s.challenge_id 
 9 | inner join Difficulty d on d.difficulty_level = c.difficulty_level and d.score = s.score
10 | inner join Hackers h on s.hacker_id = h.hacker_id 
11 | group by h.hacker_id, h.name
12 | having count(s.score) > 1
13 | order by count(s.score) desc, h.hacker_Id;


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/06. Ollivander's Inventory.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/harry-potter-and-wands/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SELECT 
 7 |     W.ID,
 8 |     WP.AGE,
 9 |     W.COINS_NEEDED,
10 |     W.POWER 
11 | FROM 
12 |     WANDS AS W
13 |     JOIN 
14 |     WANDS_PROPERTY AS WP
15 |     ON (W.CODE = WP.CODE) 
16 | WHERE 
17 |     WP.IS_EVIL = 0 
18 |     AND 
19 |     W.COINS_NEEDED=(SELECT 
20 |                         MIN(COINS_NEEDED) 
21 |                     FROM
22 |                         WANDS AS X
23 |                         JOIN 
24 |                         WANDS_PROPERTY AS Y 
25 |                         ON (X.CODE = Y.CODE) 
26 |                     WHERE 
27 |                         X.POWER = W.POWER 
28 |                         AND 
29 |                         Y.AGE = WP.AGE) 
30 | ORDER BY 
31 |     W.POWER DESC, 
32 |     WP.AGE DESC;


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/07. Challenges.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/challenges/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | select
 7 |     h.hacker_id, 
 8 |     h.name, 
 9 |     count(c.challenge_id) as cnt 
10 | from 
11 |     Hackers h 
12 |     join 
13 |     Challenges c 
14 |     on h.hacker_id = c.hacker_id 
15 | group by 
16 |     h.hacker_id,
17 |     h.name
18 | having
19 |     cnt = ( select count(challenge_id) as cn 
20 |             from Challenges 
21 |             group by hacker_id 
22 |             order by cn desc 
23 |             limit 1 ) 
24 |     or 
25 |     cnt in (select t.total 
26 |             from (select count(*) as total 
27 |                 from Challenges 
28 |                 group by hacker_id) t 
29 |             group by t.total 
30 |             having count(t.total)=1) 
31 | order by 
32 |     cnt desc,
33 |     h.hacker_id;


--------------------------------------------------------------------------------
/SQL/4. BASIC JOIN/08. Contest Leaderboard.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/contest-leaderboard/problem
 2 | -- # Score: 30
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | select 
 7 |     t.hacker_id, 
 8 |     h.name, 
 9 |     sum(t.s) as total
10 | from 
11 |     (select 
12 |         hacker_id,
13 |         challenge_id,
14 |         max(score) as s
15 |     from
16 |         Submissions
17 |     group by
18 |         hacker_id,
19 |         challenge_id
20 |     ) t
21 |     join
22 |     hackers h
23 |     on h.hacker_id= t.hacker_id
24 | group by
25 |     t.hacker_id,
26 |     h.name
27 | having 
28 |     total>0
29 | order by 
30 |     total desc,
31 |     t.hacker_id;


--------------------------------------------------------------------------------
/SQL/5. ADVANCED JOIN/01. SQL Project Planning.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/sql-projects/problem
 2 | -- # Score: 40
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | SELECT Start_Date, MIN(End_Date) FROM
 7 | (SELECT Start_Date FROM Projects WHERE Start_Date NOT IN (SELECT End_Date FROM Projects)) AS sd,
 8 | (SELECT End_Date FROM Projects WHERE End_Date NOT IN (SELECT Start_Date FROM Projects)) AS ed
 9 | WHERE Start_Date < End_Date
10 | GROUP BY Start_Date
11 | ORDER BY DATEDIFF(MIN(End_Date), Start_Date), Start_Date;


--------------------------------------------------------------------------------
/SQL/5. ADVANCED JOIN/02. SQL Symmetric Pairs.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/symmetric-pairs/problem?isFullScreen=true
 2 | -- # Score: 40
 3 | -- # Difficulty: Medium
 4 | 
 5 | 
 6 | 
 7 | SELECT DISTINCT f1.x,f1.y 
 8 | FROM   functions f1 
 9 |        inner join functions f2 
10 |                ON f1.x IN f2.y 
11 |                   AND f1.y IN f2.x 
12 | WHERE  f1.x < f1.y 
13 |         OR f1.x IN (SELECT x 
14 |                    FROM   functions 
15 |                    WHERE  x = y 
16 |                    GROUP  BY x,y 
17 |                    HAVING Count(*) > 1) 
18 | ORDER  BY f1.x; 
19 | 
20 | 


--------------------------------------------------------------------------------
/SQL/5. ADVANCED JOIN/03. 15 Days of Learning SQL.sql:
--------------------------------------------------------------------------------
 1 | -- # Problem: https://www.hackerrank.com/challenges/15-days-of-learning-sql/problem?isFullScreen=true
 2 | -- # Score: 50
 3 | -- # Difficulty: Hard
 4 | 
 5 | 
 6 | 
 7 | SELECT t1.submission_date, hkr_cnt, t2.hacker_id, name
 8 | FROM (SELECT p1.submission_date, 
 9 |              COUNT(DISTINCT p1.hacker_id) AS hkr_cnt
10 |       FROM (SELECT submission_date, hacker_id, 
11 |                    @h_rnk := CASE WHEN @h_grp != hacker_id THEN 1 ELSE @h_rnk+1 END AS hacker_rank,
12 |                    @h_grp := hacker_id AS hacker_group
13 |             FROM (SELECT DISTINCT submission_date, hacker_id 
14 |                   FROM submissions
15 |                   ORDER BY hacker_id, submission_date) AS a, 
16 |                  (SELECT @h_rnk := 1, @h_grp := 0) AS r) AS p1
17 |       JOIN (SELECT submission_date, 
18 |                    @d_rnk := @d_rnk + 1 AS date_rank
19 |             FROM (SELECT DISTINCT submission_date
20 |                   FROM submissions 
21 |                   ORDER BY submission_date) AS b, 
22 |                  (SELECT @d_rnk := 0) r) AS p2
23 |       ON p1.submission_date = p2.submission_date 
24 |          AND hacker_rank = date_rank
25 |       GROUP BY p1.submission_Date) AS t1
26 | JOIN (SELECT submission_date, hacker_id, sub_cnt,
27 |              @s_rnk := CASE WHEN @d_grp != submission_date THEN 1 ELSE @s_rnk+1 END AS max_rnk,
28 |              @d_grp := submission_date AS date_group
29 |       FROM (SELECT submission_date, hacker_id, COUNT(*) AS sub_cnt
30 |             FROM submissions AS s
31 |             GROUP BY submission_date, hacker_id
32 |             ORDER BY submission_date, sub_cnt DESC, hacker_id) AS c,
33 |            (SELECT @s_rnk := 1, @d_grp := 0) AS r) AS t2                            
34 | ON t1.submission_date = t2.submission_date AND max_rnk = 1
35 | JOIN hackers AS h ON h.hacker_id = t2.hacker_id            
36 | ORDER BY t1.submission_date
37 | ;
38 | 


--------------------------------------------------------------------------------
/SQL/5. ADVANCED JOIN/Interviews.sql:
--------------------------------------------------------------------------------
 1 | --PROBLEM LINK
 2 | --https://www.hackerrank.com/challenges/interviews/problem?isFullScreen=true
 3 | 
 4 | --PROBLEM NAME
 5 | --Interviews
 6 | 
 7 | --LANGUAGE
 8 | --SQL
 9 | 
10 | --SUBDOMAIN
11 | --Advanced Join
12 | 
13 | --MAX SCORE
14 | --50
15 | 
16 | --DIFFICULTY
17 | --Hard
18 | 
19 | 
20 | WITH total_submit as (
21 | 
22 |     SELECT
23 |             coll.contest_id,
24 |             SUM(ss.total_submissions) as sumts,
25 |             SUM(ss.total_accepted_submissions) as sumtas
26 | FROM        Colleges coll
27 | INNER JOIN  Challenges chall    ON chall.college_id = coll.college_id
28 | INNER JOIN  Submission_Stats ss ON chall.challenge_id = ss.challenge_id
29 | GROUP BY    coll.contest_id
30 |     
31 | ),
32 | 
33 | total_view as (
34 | 
35 |     SELECT
36 |             coll.contest_id,
37 |             SUM(vs.total_views) as sumtv,
38 |             SUM(vs.total_unique_views) as sumtuv
39 | FROM        Colleges coll
40 | INNER JOIN  Challenges chall ON chall.college_id = coll.college_id
41 | INNER JOIN  View_Stats vs    ON chall.challenge_id = vs.challenge_id
42 | GROUP BY    coll.contest_id
43 | 
44 | )
45 | 
46 | SELECT
47 |             cont.contest_id,
48 |             cont.hacker_id,
49 |             cont.name,
50 |             ts.sumts,
51 |             ts.sumtas,
52 |             tv.sumtv,
53 |             tv.sumtuv
54 | FROM        Contests cont
55 | INNER JOIN  total_submit ts ON ts.contest_id = cont.contest_id
56 | INNER JOIN  total_view   tv ON tv.contest_id = cont.contest_id
57 | WHERE       ts.sumts  > 0
58 | OR          ts.sumtas > 0
59 | OR          tv.sumtv  > 0
60 | OR          tv.sumtuv > 0
61 | ORDER BY    cont.contest_id
62 | ;
63 | 


--------------------------------------------------------------------------------
/SQL/6. ALTERNATIVE QUERIES/01. Draw The Triangle 1.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/draw-the-triangle-1/problem
2 | -- # Score: 25
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SET @num = 21;
7 | SELECT REPEAT('* ', @num := @num - 1)
8 | FROM information_schema.tables 
9 | WHERE @num > 0;


--------------------------------------------------------------------------------
/SQL/6. ALTERNATIVE QUERIES/02. Draw The Triangle 2.sql:
--------------------------------------------------------------------------------
1 | -- # Problem: https://www.hackerrank.com/challenges/draw-the-triangle-2/problem
2 | -- # Score: 25
3 | -- # Difficulty: Easy
4 | 
5 | 
6 | SET @num = 0;
7 | SELECT REPEAT('* ', @num := @num + 1) 
8 | FROM information_schema.tables 
9 | limit 20;


--------------------------------------------------------------------------------