├── practice ├── algorithms │ ├── insertionSort.js │ ├── selectionSort.js │ └── binarySearch.js ├── data_structures │ ├── HashTable.js │ ├── Dictionary.js │ ├── Set.js │ └── LinkedList.js ├── searching-algorithms.js ├── dynamic-programming.js ├── readme.md ├── recursion.js └── exercises.js ├── .DS_Store ├── udemy-interview-bootcamp-course ├── .DS_Store ├── data_structures │ ├── stack.js │ ├── queue.js │ ├── trees.js │ └── linked_list.js ├── README.md ├── 05_fizzbuzz.js ├── 03_integer_reversal.js ├── 17_circular.js ├── 01_string_reversal.js ├── 16_midpoint.js ├── 18_from_last.js ├── 11_vowels.js ├── 09_steps.js ├── 19_level_width.js ├── 04_max_chars.js ├── 02_palindromes.js ├── 10_pyramids.js ├── 08_capitalize.js ├── 12_spiral_matrix.js ├── 15_qfroms.js ├── 14_weave.js ├── 13_fib.js ├── 06_array_chunking.js └── 07_anagrams.js ├── data-structures ├── algorithms-2018-08-outline.pdf └── curriculum.md ├── interviewcake ├── readme.md ├── arrays │ ├── 05-makeChange.js │ ├── 13-rotateWords.js │ ├── 12-orderedSet.js │ ├── 26-reverse-in-place.js │ ├── 03-highestProductOf3.js │ ├── 02-productOfOtherNumbers.js │ └── 01-appleStock.js └── hashTables │ ├── 30-checkPalindrome.js │ └── 14-inflight-entertainment.js ├── flexbox ├── index.html ├── readme.md ├── navigation.html └── style.css ├── hackerrank └── readme.md ├── sql ├── 02-relational-queries.sql └── 01-sql-queries.sql └── README.md /practice/algorithms/insertionSort.js: -------------------------------------------------------------------------------- 1 | -------------------------------------------------------------------------------- /practice/data_structures/HashTable.js: -------------------------------------------------------------------------------- 1 | -------------------------------------------------------------------------------- /.DS_Store: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/sabir4063/coding-interviews/HEAD/.DS_Store -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/.DS_Store: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/sabir4063/coding-interviews/HEAD/udemy-interview-bootcamp-course/.DS_Store -------------------------------------------------------------------------------- /data-structures/algorithms-2018-08-outline.pdf: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/sabir4063/coding-interviews/HEAD/data-structures/algorithms-2018-08-outline.pdf -------------------------------------------------------------------------------- /practice/data_structures/Dictionary.js: -------------------------------------------------------------------------------- 1 | function Dictionary(){ 2 | var items = {}; 3 | 4 | this.set = (key, value) => { 5 | 6 | } 7 | 8 | this.delete = (key) => { 9 | 10 | } 11 | 12 | this.has = (key) => { 13 | 14 | } 15 | 16 | this.get = (key) => { 17 | 18 | } 19 | 20 | this.clear = () => { 21 | 22 | } 23 | 24 | this.size = () => { 25 | 26 | } 27 | 28 | this.keys = () => { 29 | 30 | } 31 | 32 | this.values = () => { 33 | 34 | } 35 | } -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/data_structures/stack.js: -------------------------------------------------------------------------------- 1 | // Stack - FILO - First In, Last Out 2 | 3 | // pushing - add to stack 4 | // popping - remove from stack 5 | 6 | class Stack { 7 | constructor(){ 8 | this.data = []; 9 | } 10 | 11 | push(item){ 12 | this.data.push(item); 13 | } 14 | 15 | pop(){ 16 | return this.data.pop(); 17 | } 18 | 19 | peek(){ 20 | return this.data[this.data.length - 1]; 21 | } 22 | 23 | } 24 | 25 | module.exports = Stack; -------------------------------------------------------------------------------- /practice/searching-algorithms.js: -------------------------------------------------------------------------------- 1 | // https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/searching-algorithms 2 | 3 | // Algorithms: Graph Search, DFS and BFS by author of CTCI: https://www.youtube.com/watch?v=zaBhtODEL0w 4 | 5 | // Algorithm course on Coderbyte: 6 | // https://coderbyte.com/course/learn-data-structures-and-algorithms/ 7 | // https://coderbyte.com/course/trees-and-graphs 8 | // https://coderbyte.com/course/arrays-and-lists 9 | 10 | 11 | 12 | -------------------------------------------------------------------------------- /interviewcake/readme.md: -------------------------------------------------------------------------------- 1 | 2 | A **greedy algorithm** iterates through the problem space taking the optimal solution "so far" 3 | until it reaches the end. 4 | 5 | Greedy approaches are great because they are fast (usually one pass through the input). 6 | 7 | Ask yourself, suppose we could come up with the answer for one pass through the input by 8 | updating the 'best answer so far' as we went. What additional values would we need to keep 9 | updated as we looked at each item in our set, in order to be able to update the 'best answer 10 | so far'? -------------------------------------------------------------------------------- /interviewcake/arrays/05-makeChange.js: -------------------------------------------------------------------------------- 1 | // dynamic programming question. 2 | 3 | 4 | 5 | // Write a function that, given: 6 | 7 | // an amount of money 8 | // an array of coin denominations 9 | 10 | // computes the number of ways to make the amount of money with coins of the available denominations. 11 | 12 | var amount1 = 4; 13 | var denominations1 = [1,2,3]; 14 | 15 | console.log(makeChange(amount1, denominations1)); 16 | 17 | function makeChange(amount, denominations){ 18 | 19 | 20 | } 21 | 22 | // brute force approach is to see if we can get to amount with repeatedly doing e -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/data_structures/queue.js: -------------------------------------------------------------------------------- 1 | // Queue = container. enter in one end and exit on the other. 2 | // First In, First Out (FIFO) 3 | 4 | // Methods: 5 | // enqueue - add to queue 6 | // dequeue - remove from queue 7 | 8 | class Queue { 9 | constructor(){ 10 | this.queue = []; 11 | } 12 | add(item){ 13 | this.queue.unshift(item); 14 | } 15 | 16 | remove(){ 17 | return this.queue.pop(); 18 | } 19 | 20 | // View the next element to be removed from the queue 21 | peek(){ 22 | return this.queue[this.queue.length - 1]; 23 | } 24 | } 25 | 26 | module.exports = Queue; -------------------------------------------------------------------------------- /interviewcake/arrays/13-rotateWords.js: -------------------------------------------------------------------------------- 1 | var words = [ 2 | 'ptolemaic', 3 | 'retrograde', 4 | 'supplant', 5 | 'undulate', 6 | 'xenoepist', 7 | 'asymptote', // <-- rotates here! 8 | 'babka', 9 | 'banoffee', 10 | 'engender', 11 | 'karpatka', 12 | 'othellolagkage', 13 | ]; 14 | 15 | console.log(rotateWords(words)); 16 | 17 | function rotateWords(wordList){ 18 | var max = wordList.length - 1; 19 | var min = 0; 20 | var guess; 21 | 22 | while(max >= min){ 23 | guess = Math.floor((max+min)/2); 24 | 25 | if(wordList[guess] >wordList[max]) ){ 26 | console.log() 27 | } 28 | } 29 | 30 | } -------------------------------------------------------------------------------- /interviewcake/arrays/12-orderedSet.js: -------------------------------------------------------------------------------- 1 | 2 | var sorted = [1,2,3,4,5,6,7,8,400]; 3 | console.log(findInOrderedSet(sorted, 69)); 4 | 5 | // binary search 6 | function findInOrderedSet(sorted, num){ 7 | var min = 0; 8 | var max = sorted.length - 1; 9 | var guess; 10 | 11 | while(max >= min){ 12 | guess = Math.floor((max+min)/2); 13 | 14 | if(sorted[guess] == num) return true; 15 | 16 | if(sorted[guess] > num){ 17 | max = guess - 1; 18 | } else if (sorted[guess] < num) { 19 | min = guess + 1; 20 | } 21 | } 22 | 23 | return false; 24 | } 25 | 26 | // brute force would be loop through array 27 | // and check if # is current -------------------------------------------------------------------------------- /flexbox/index.html: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | FlexBox Tutorial 6 | 7 | 8 | 9 | 10 |
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22 | 23 | 24 | -------------------------------------------------------------------------------- /interviewcake/arrays/26-reverse-in-place.js: -------------------------------------------------------------------------------- 1 | // Write a function to reverse a string in-place 2 | 3 | var string = 'hello'; 4 | console.log(reverseString(string)); // olleh 5 | 6 | // in es6 we can also do [b,a] = [a,b]; 7 | 8 | function reverseString(str){ 9 | var startIndex = 0; 10 | var endIndex = str.length - 1; 11 | var stringArray = str.split(''); 12 | 13 | while(startIndex < endIndex){ 14 | var temp = stringArray[endIndex]; 15 | stringArray[endIndex] = stringArray[startIndex]; 16 | stringArray[startIndex] = temp; 17 | 18 | // ES6 Method: Destructuring 19 | // [stringArray[endIndex], stringArray[startIndex]] = [stringArray[startIndex], stringArray[endIndex]] 20 | 21 | startIndex++; 22 | endIndex--; 23 | } 24 | 25 | return stringArray.join(''); 26 | } -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/README.md: -------------------------------------------------------------------------------- 1 | # The Coding Interview Bootcamp: Algorithms + Data Structures 2 | 3 | 4 | Udemy course link: [The Coding Interview Bootcamp: Algorithms + Data Structures](https://www.udemy.com/coding-interview-bootcamp-algorithms-and-data-structure) 5 | 6 | [Source code](https://github.com/StephenGrider/algocasts) for the lessons. 7 | 8 | ## Additional Resources 9 | 10 | ### Regular Expressions 11 | 12 | - An Introduction to Regular Expressions (Regex) In JavaScript ([Medium article](https://codeburst.io/an-introduction-to-regular-expressions-regex-in-javascript-1d3559e7ac9a)) 13 | 14 | - Chapter 9: Regular Expressions ([Eloquent Javascript](https://eloquentjavascript.net/09_regexp.html)) 15 | 16 | - Regular Expressions ([Javascript.info](https://javascript.info/regular-expressions)) 17 | 18 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/05_fizzbuzz.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a program that console logs the numbers 3 | // from 1 to n. But for multiples of three print 4 | // “fizz” instead of the number and for the multiples 5 | // of five print “buzz”. For numbers which are multiples 6 | // of both three and five print “fizzbuzz”. 7 | // --- Example 8 | // fizzBuzz(5); 9 | // 1 10 | // 2 11 | // fizz 12 | // 4 13 | // buzz 14 | 15 | 16 | function fizzBuzz(integer){ 17 | let output = ''; 18 | for(var i = 1; i <= integer; i++){ 19 | if(i % 3 === 0 && i % 5 === 0){ 20 | output = "fizzbuzz"; 21 | } else if (i % 3 === 0){ 22 | output = "fizz"; 23 | } else if (i % 5 === 0){ 24 | output = "buzz"; 25 | } else { 26 | output = i; 27 | } 28 | console.log(output); 29 | } 30 | } 31 | 32 | fizzBuzz(15); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/03_integer_reversal.js: -------------------------------------------------------------------------------- 1 | 2 | // reverseInteger(500) === 5 3 | // reverseInteger(981) === 189 4 | // reverseInteger(-15) === -51 5 | // reverseInteger(-90) === -9 6 | 7 | function reverseInteger(integer) { 8 | let isNegative = false; 9 | 10 | if(integer < 0) isNegative = true; 11 | 12 | const reversed = String(integer).split('').reverse().join(''); 13 | 14 | return (isNegative) ? parseInt(`-${reversed}`) : parseInt(`${reversed}`); 15 | } 16 | 17 | 18 | 19 | // You can use Math.sign to determine the +/- of a number 20 | // (could use reverse function as above) 21 | 22 | function reverseIntegerSolution(integer){ 23 | const reversed = integer.toString().split('').reduce((current, accum)=>{ 24 | return accum + current; 25 | }, ''); 26 | 27 | return Math.sign(integer) * parseInt(reversed); 28 | } 29 | 30 | console.log(reverseIntegerSolution(-15)); 31 | -------------------------------------------------------------------------------- /practice/data_structures/Set.js: -------------------------------------------------------------------------------- 1 | function Set() { 2 | let items = {}; 3 | 4 | this.add = (value) => { 5 | if(!this.has(value)){ 6 | items[value] = value; 7 | return true; 8 | } 9 | return false; 10 | } 11 | 12 | this.delete = (value) => { 13 | // verify value exists 14 | if(this.has(value)){ 15 | delete items[value]; 16 | return true; 17 | } 18 | return false; 19 | } 20 | 21 | this.has = (value) => { 22 | // returns boolean if property exists 23 | return items.hasOwnProperty(value); 24 | } 25 | 26 | this.clear = () => { 27 | items = {}; 28 | } 29 | 30 | this.size = () => { 31 | return Object.keys(items).length; 32 | } 33 | 34 | this.values = () => { 35 | 36 | } 37 | } 38 | 39 | 40 | // union 41 | 42 | // intersection 43 | 44 | // difference 45 | 46 | // subset -------------------------------------------------------------------------------- /interviewcake/hashTables/30-checkPalindrome.js: -------------------------------------------------------------------------------- 1 | // Write an efficient function that checks whether any permutation 2 | // of an input string is a palindrome 3 | 4 | // "civic" should return true 5 | // "ivicc" should return true 6 | // "civil" should return false 7 | // "livci" should return false 8 | 9 | console.log(checkPalindrome("civic")); 10 | console.log(checkPalindrome("ivicc")); 11 | console.log(checkPalindrome("civil")); 12 | console.log(checkPalindrome("livci")); 13 | 14 | function checkPalindrome(str){ 15 | var hashMap = {}; 16 | 17 | for(var i = 0; i< str.length; i++){ 18 | (hashMap[str[i]]) ? hashMap[str[i]] += 1 : hashMap[str[i]] = 1; 19 | } 20 | 21 | var countsGreaterThanOne = 0; 22 | var oneCounts = 0; 23 | 24 | for(var k in hashMap){ 25 | var count = hashMap[k]; 26 | if(count == 1) oneCounts += 1; 27 | } 28 | 29 | return (oneCounts >= 2 ) ? false : true; 30 | 31 | 32 | } -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/17_circular.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given a linked list, return true if the list 3 | // is circular, false if it is not. 4 | // --- Examples 5 | // const l = new List(); 6 | // const a = new Node('a'); 7 | // const b = new Node('b'); 8 | // const c = new Node('c'); 9 | // l.head = a; 10 | // a.next = b; 11 | // b.next = c; 12 | // c.next = b; 13 | // circular(l) // true 14 | 15 | const { LinkedList } = require('./data_structures/linked_list'); 16 | 17 | function circular(list){ 18 | let slow = list.head; 19 | let fast = list.head; 20 | 21 | while(fast.next && fast.next.next){ 22 | slow = slow.next; 23 | fast = fast.next.next; 24 | 25 | if(slow === fast){ 26 | return true; 27 | } 28 | } 29 | 30 | return false; 31 | } 32 | 33 | let list = new LinkedList(); 34 | list.insertLast('a'); 35 | list.insertLast('b'); 36 | list.insertLast('c'); 37 | 38 | console.log(list); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/01_string_reversal.js: -------------------------------------------------------------------------------- 1 | /* 2 | 3 | Given a string, return a new string with the reversed 4 | order of characters 5 | 6 | reverse('apple') => 'elppa' 7 | */ 8 | 9 | function reverse(str){ 10 | let result = ''; 11 | for(var i = str.length; i >= 0; i--){ 12 | result += str.charAt(i); 13 | } 14 | return result; 15 | } 16 | 17 | // use built in array and string 18 | function reverseSolution1(str){ 19 | return str.split('') 20 | .reverse() 21 | .join(''); 22 | } 23 | 24 | // use for ... of and prepend 25 | function reverseSolution2(str){ 26 | let result = ''; 27 | for(let char of str){ 28 | result = char + result; 29 | } 30 | return result; 31 | } 32 | 33 | // use array reduce 34 | function reverseSolution3(str){ 35 | return str 36 | .split('') 37 | .reduce((result, letter)=> letter + result, ''); 38 | } 39 | 40 | console.log(reverseSolution3('hello')); 41 | 42 | module.exports = reverse; -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/16_midpoint.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Return the 'middle' node of a linked list. 3 | // If the list has an even number of elements, return 4 | // the node at the end of the first half of the list. 5 | // *Do not* use a counter variable, *do not* retrieve 6 | // the size of the list, and only iterate 7 | // through the list one time. 8 | // --- Example 9 | // const l = new LinkedList(); 10 | // l.insertLast('a') 11 | // l.insertLast('b') 12 | // l.insertLast('c') 13 | // midpoint(l); // returns { data: 'b' } 14 | 15 | const { LinkedList } = require('./data_structures/linked_list'); 16 | 17 | function midpoint(list){ 18 | let slow = list.getFirst(); 19 | let fast = list.getFirst(); 20 | 21 | while(fast.next && fast.next.next){ 22 | slow = slow.next; 23 | fast = fast.next.next; 24 | } 25 | 26 | return slow; 27 | } 28 | 29 | let list = new LinkedList(); 30 | list.insertLast('a'); 31 | list.insertLast('b'); 32 | list.insertLast('c'); 33 | list.insertLast('d'); 34 | 35 | console.log(midpoint(list)); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/18_from_last.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given a linked list, return the element n spaces 3 | // from the last node in the list. Do not call the 'size' 4 | // method of the linked list. Assume that n will always 5 | // be less than the length of the list. 6 | // --- Examples 7 | // const list = new List(); 8 | // list.insertLast('a'); 9 | // list.insertLast('b'); 10 | // list.insertLast('c'); 11 | // list.insertLast('d'); 12 | // fromLast(list, 2).data // 'b' 13 | 14 | const { LinkedList } = require('./data_structures/linked_list'); 15 | 16 | function fromLast(list, n){ 17 | let slow = list.head; 18 | let fast = list.head; 19 | 20 | while(n > 0){ 21 | fast = fast.next; 22 | n--; 23 | } 24 | 25 | while(fast.next){ 26 | slow = slow.next; 27 | fast = fast.next; 28 | } 29 | 30 | return slow; 31 | } 32 | 33 | 34 | const list = new LinkedList(); 35 | list.insertLast('a'); 36 | list.insertLast('b'); 37 | list.insertLast('c'); 38 | list.insertLast('d'); 39 | console.log(fromLast(list, 2).data) // 'b' 40 | 41 | -------------------------------------------------------------------------------- /practice/data_structures/LinkedList.js: -------------------------------------------------------------------------------- 1 | 2 | function LinkedList() { 3 | 4 | // helper class 5 | let Node = function(elem){ 6 | this.element = elem; 7 | this.next = null; 8 | } 9 | 10 | let length = 0; 11 | 12 | // reference to first node 13 | let head = null; 14 | 15 | // reference to the last node 16 | let tail = null; 17 | 18 | // adds element to the end 19 | this.append = (elem) => { 20 | 21 | } 22 | 23 | // insert item at specified index 24 | this.insert = (position, elem) => { 25 | 26 | } 27 | 28 | // remove element from specified position 29 | this.removeAt = (position) => { 30 | 31 | } 32 | 33 | // remove item from list 34 | this.remove = (elem) => { 35 | 36 | } 37 | 38 | // return index of element or -1 if not present 39 | this.indexOf = (elem) => { 40 | 41 | } 42 | 43 | // returns true if no elements in list 44 | this.isEmpty = () => { 45 | 46 | } 47 | 48 | // returns number of elements 49 | this.size = () => { 50 | 51 | } 52 | 53 | // output element values 54 | this.toString = () => { 55 | 56 | } 57 | 58 | this.print = () => { 59 | 60 | } 61 | } 62 | 63 | new LinkedList(); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/11_vowels.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a function that returns the number of vowels 3 | // used in a string. Vowels are the characters 'a', 'e' 4 | // 'i', 'o', and 'u'. 5 | // --- Examples 6 | // vowels('Hi There!') --> 3 7 | // vowels('Why do you ask?') --> 4 8 | // vowels('Why?') --> 0 9 | 10 | function vowels(str) { 11 | let count = 0; 12 | 13 | str.split('').map((letter)=>{ 14 | letter = letter.toLowerCase() || null; 15 | if(letter == 'a' || letter == 'e' || letter == 'i' || letter == 'o' || letter == 'u'){ 16 | count++; 17 | } 18 | }); 19 | 20 | return count; 21 | } 22 | 23 | 24 | 25 | 26 | // Could uss a for ... of loop 27 | function vowels(str) { 28 | let count = 0; 29 | const checker = ['a', 'e', 'i', 'o', 'u']; 30 | 31 | for (let char of str.toLowerCase()) { 32 | if (checker.includes(char)) { 33 | count++; 34 | } 35 | } 36 | 37 | return count; 38 | } 39 | 40 | 41 | 42 | 43 | // or a regular expression: 44 | function vowels(str) { 45 | const matches = str.match(/[aeiou]/gi); 46 | return matches ? matches.length : 0; 47 | } 48 | 49 | 50 | 51 | console.log(vowels('Why do you ask?')); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/09_steps.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a function that accepts a positive number N. 3 | // The function should console log a step shape 4 | // with N levels using the # character. Make sure the 5 | // step has spaces on the right hand side! 6 | // --- Examples 7 | // steps(2) 8 | // '# ' 9 | // '##' 10 | // steps(3) 11 | // '# ' 12 | // '## ' 13 | // '###' 14 | // steps(4) 15 | // '# ' 16 | // '## ' 17 | // '### ' 18 | // '####' 19 | 20 | 21 | function steps(size){ 22 | 23 | for(let row = 0; row < size; row++){ 24 | let step = ''; 25 | 26 | for(let column = 0; column < size; column++){ 27 | if(row >= column){ 28 | step += '#'; 29 | } else { 30 | step += ' '; 31 | } 32 | 33 | } 34 | console.log(step); 35 | } 36 | } 37 | 38 | function stepsRecursive(size, row = 0, step = ''){ 39 | // base case 40 | if(size === row){ 41 | return; 42 | } 43 | 44 | // move on to next row 45 | if(size === step.length){ 46 | console.log(step); 47 | return stepsRecursive(size, row + 1); 48 | } 49 | 50 | // build current row 51 | step += (step.length <= row) ? '#' : ' '; 52 | 53 | stepsRecursive(size, row, step); 54 | } 55 | 56 | stepsRecursive(4); 57 | 58 | 59 | -------------------------------------------------------------------------------- /flexbox/readme.md: -------------------------------------------------------------------------------- 1 | CSS Flexbox 2 | === 3 | 4 | - What the Flexbox by @wesbos - https://flexbox.io/ 5 | 6 | - Complete Guide to Flexbox by @CSS-Tricks - https://css-tricks.com/snippets/css/a-guide-to-flexbox/ 7 | 8 | Can display `flex` or `inline-flex`for the `display:` CSS property. 9 | 10 | `height:100vh` gives element 100% viewport height 11 | 12 | `flex-direction: row;` is default. It makes the main axis from left to right. Cross axis goes from top to bottom. 13 | 14 | `flex-direction: column` stacks them. It makes the main axis from top to bottom. The cross axis becomes left to right. 15 | 16 | The reverse flag can be added to these to make right to left (`row-reverse`) or `column-reverse` where main axis goes from bottom to top. 17 | 18 | flex-wrap... 19 | 20 | `calc()` in CSS can incorporate margins. So `width:33%;margin:10px` will break but `width:calc(33%-20px);margin:10px;` will take care of the 10px on each side and show 3 boxes. 21 | 22 | `border` and `padding` is part of the box model. `margin` is not part of the box model. 23 | 24 | Add vendor prefixes to our code to make sure that all browsers accept our code. 25 | 26 | - Online tool: https://autoprefixer.github.io/ 27 | 28 | - autoprefixer github: https://github.com/postcss/autoprefixer 29 | 30 | - for webpack: https://github.com/postcss/postcss-loader 31 | 32 | -------------------------------------------------------------------------------- /interviewcake/hashTables/14-inflight-entertainment.js: -------------------------------------------------------------------------------- 1 | var flightTime = 240; 2 | var movies = [60, 117, 121, 54, 239, 62, 120, 120, 58]; 3 | 4 | console.log(chooseMovies(flightTime, movies)); 5 | 6 | 7 | function chooseMovies(flightLength, movieLengths){ 8 | var hashMap = {}; 9 | 10 | for(var i = 0; i < movieLengths.length; i++){ 11 | (hashMap[movieLengths[i]]) ? hashMap[movieLengths[i]]+=1 : hashMap[movieLengths[i]] = 1; 12 | } 13 | 14 | for(var i = 0; i < movieLengths.length; i++){ 15 | var difference = flightTime - movieLengths[i]; 16 | 17 | if(hashMap[difference] && difference !== movieLengths[i]){ 18 | return true; 19 | } 20 | 21 | if(difference == movieLengths[i] && hashMap[difference] >= 2){ 22 | return true; 23 | } 24 | 25 | } 26 | 27 | return false; 28 | } 29 | 30 | 31 | // Brute force solution is for every movie go through and compare 32 | // if any other movie adds up to flightLength 33 | // function chooseMovies(flightLength, movieLengths){ 34 | 35 | // for(var i = 0; i < movieLengths.length; i++){ 36 | // var movie = movieLengths[i]; 37 | 38 | // for(var j = 0; j < movieLengths.length; j++){ 39 | // var compare = movieLengths[j]; 40 | 41 | // if(movie + compare === flightLength && i !== j) { 42 | // return true; 43 | // } 44 | // } 45 | // } 46 | // return false; 47 | // } -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/19_level_width.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given the root node of a tree, return 3 | // an array where each element is the width 4 | // of the tree at each level. 5 | // --- Example 6 | // Given: 7 | // 0 8 | // / | \ 9 | // 1 2 3 10 | // | | 11 | // 4 5 12 | // Answer: [1, 3, 2] 13 | 14 | const { Node } = require('./data_structures/trees'); 15 | 16 | function levelWidth(root) { 17 | let counters = []; 18 | let rowCount = 0; 19 | let queue = [root, 'STOP']; 20 | 21 | while(queue.length){ 22 | 23 | let first = queue.shift(); 24 | 25 | if (first === 'STOP') { 26 | counters.push(rowCount); 27 | rowCount = 0; 28 | 29 | if(queue.length){ 30 | queue.push('STOP'); 31 | } 32 | 33 | continue; 34 | } 35 | 36 | queue.push(...first.children); 37 | rowCount += 1; 38 | } 39 | 40 | return counters; 41 | 42 | } 43 | 44 | const root = new Node(0); 45 | root.add(1); 46 | root.add(2); 47 | root.add(3); 48 | root.children[0].add(4); 49 | root.children[2].add(5); 50 | 51 | console.log(levelWidth(root)) // [1, 3, 2] 52 | 53 | const root2 = new Node(0); 54 | root2.add(1); 55 | root2.children[0].add(2); 56 | root2.children[0].add(3); 57 | root2.children[0].children[0].add(4); 58 | 59 | console.log(levelWidth(root2)) // [1, 1, 2, 1] 60 | -------------------------------------------------------------------------------- /practice/algorithms/selectionSort.js: -------------------------------------------------------------------------------- 1 | // Find the smallest card. Swap it with the first card. 2 | // Find the second-smallest card. Swap it with the second card. 3 | // Find the third-smallest card. Swap it with the third card. 4 | // Repeat finding the next-smallest card, and swapping it into the correct position until the array is sorted. 5 | // This algorithm is called selection sort because it repeatedly selects the next-smallest element and swaps it into place. 6 | 7 | // O(n^2) 8 | 9 | var swap = function(array, firstIndex, secondIndex) { 10 | var temp = array[secondIndex]; 11 | array[secondIndex] = array[firstIndex]; 12 | array[firstIndex] = temp; 13 | }; 14 | 15 | var indexOfMinimum = function(array, startIndex) { 16 | var minValue = array[startIndex]; 17 | var minIndex = startIndex; 18 | 19 | for(var i = startIndex + 1; i < array.length; i++){ 20 | if(array[i] < minValue) { 21 | minValue = array[i]; 22 | minIndex = i; 23 | } 24 | } 25 | 26 | return minIndex; 27 | }; 28 | 29 | var selectionSort = function(array) { 30 | for(var i = 0; i< array.length; i++){ 31 | var min = indexOfMinimum(array, i); 32 | swap(array, i, min); 33 | } 34 | return array; 35 | }; 36 | 37 | var array = [22, 11, 99, 88, 9, 7, 42]; 38 | selectionSort(array); 39 | console.log("Array after sorting: " + array); 40 | 41 | 42 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/04_max_chars.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given a string, return the character that is most 3 | // commonly used in the string. 4 | // --- Examples 5 | // maxChar("abcccccccd") === "c" 6 | // maxChar("apple 1231111") === "1" 7 | 8 | function maxChar(str) { 9 | let map = {}; 10 | let maxCount = 0; 11 | let letter; 12 | 13 | str.split('').forEach((letter)=>{ 14 | map[letter] = (map[letter]) ? map[letter] + 1 : 1; 15 | }); 16 | 17 | for(key in map){ 18 | if(map[key] > maxCount){ 19 | maxCount = map[key]; 20 | letter = key; 21 | } 22 | 23 | } 24 | 25 | return letter; 26 | } 27 | 28 | 29 | 30 | function maxCharSolution(str){ 31 | const charMap = {}; 32 | let max = 0; 33 | let maxChar = ''; 34 | 35 | for(let char of str) { 36 | if(charMap[char]){ 37 | charMap[char]++; 38 | } else { 39 | charMap[char] = 1; 40 | } 41 | } 42 | 43 | for(char in charMap){ 44 | if(charMap[char] > max){ 45 | max = charMap[char]; 46 | maxChar = char; 47 | } 48 | } 49 | 50 | return maxChar; 51 | } 52 | 53 | console.log(maxCharSolution("abcccccccd")); 54 | 55 | 56 | /****************** 57 | Most common string questions: 58 | 59 | - What is the most common character in this string? 60 | - Does string A have the same characters as string B? (anagram) 61 | - Does the string have any repeating characters in it? 62 | ******************/ -------------------------------------------------------------------------------- /practice/dynamic-programming.js: -------------------------------------------------------------------------------- 1 | // https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/dynamic-programming 2 | 3 | // memoization = 'storing' the result of an expensive function 4 | // Memoization is implemented by maintaining a lookup table of previous solved sub-problems 5 | 6 | // tabulation you solve the by solving all related sub-problems first 7 | 8 | // Video from CTCI - Algorithms: Memoization and Dynamic Programming - https://www.youtube.com/watch?v=P8Xa2BitN3I 9 | 10 | // Lots of extra dynammic programming problems - http://www.geeksforgeeks.org/dynamic-programming/ 11 | 12 | //======= 13 | 14 | // Knapsack Problem 15 | // given a set of positive integers, 3, 5, 6, 10, 34 say, find a subset that sums 16 | // to exactly to a given value, such as 50. 17 | var ints = [3, 5, 6, 10, 34] 18 | var value = 50 19 | 20 | console.log(knapsack(ints, value)); // [6, 10, 34] 21 | 22 | function knapsack(arr, value){ 23 | 24 | } 25 | 26 | // Change Making Problem 27 | // https://www.interviewcake.com/question/javascript/coin 28 | 29 | 30 | // Fibonacci Sequence 31 | // [0,1,1,2,3,5,8,13,21] 32 | 33 | // console.log(fib(9)); 34 | 35 | function fib(i){ 36 | let dict = {}, output = Array(i).fill(0); output[1] = 1; 37 | 38 | for(let j = 2; j < output.length; j++){ 39 | if(output[j] == 0){ 40 | output[j] = output[j-1] + output[j-2] 41 | } 42 | } 43 | return output; 44 | 45 | } -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/02_palindromes.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given a string, return true if the string is a palindrome 3 | // or false if it is not. Palindromes are strings that 4 | // form the same word if it is reversed. *Do* include spaces 5 | // and punctuation in determining if the string is a palindrome. 6 | // --- Examples: 7 | // palindrome("abba") === true 8 | // palindrome("abcdefg") === false 9 | 10 | function palindrome(str){ 11 | const middle = Math.floor(str.length/2); 12 | 13 | const firsthalf = str.substring(0, middle); 14 | const secondhalf = (str.length % 2 === 0)? str.substring(middle) : str.substring(middle + 1); 15 | 16 | return (firsthalf === reverse(secondhalf)); 17 | } 18 | 19 | function reverse(str){ 20 | return str.split('').reduce((accum, letter)=> letter + accum, ''); 21 | } 22 | 23 | 24 | // first solution. No need for splitting the terms into halves! 25 | function palindromeSolution1(str){ 26 | const reversed = str.split('').reduce((accum, letter)=> letter + accum, ''); 27 | return reversed === str; 28 | } 29 | 30 | 31 | // second solution: compare each letter from beginning and end of array 32 | function palindromeSolution2(str){ 33 | return str.split('').every((current, index, arr)=>{ 34 | return (current === arr[arr.length - index - 1]); 35 | }); 36 | } 37 | 38 | console.log(palindromeSolution2("abba")); 39 | console.log(palindromeSolution2("abcdefg")); -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/10_pyramids.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a function that accepts a positive number N. 3 | // The function should console log a pyramid shape 4 | // with N levels using the # character. Make sure the 5 | // pyramid has spaces on both the left *and* right hand sides 6 | // --- Examples 7 | // pyramid(1) 8 | // '#' 9 | // pyramid(2) 10 | // ' # ' 11 | // '###' 12 | // pyramid(3) 13 | // ' # ' 14 | // ' ### ' 15 | // '#####' 16 | 17 | function pyramids(height){ 18 | const midpoint = Math.floor((2 * height - 1) / 2); 19 | 20 | 21 | for(var row = 0; row < height; row++){ 22 | let block = ''; 23 | 24 | for(var column = 0; column < 2 * height - 1; column++){ 25 | 26 | block += (midpoint - row <= column && midpoint + row >= column) ? '#' : ' '; 27 | } 28 | console.log(block); 29 | } 30 | 31 | } 32 | 33 | 34 | function pyramidsRecursive(height, row = 0, level = ''){ 35 | if(row === height) return; 36 | 37 | if(level.length === 2 * height - 1){ 38 | console.log(level); 39 | return pyramidsRecursive(height, row + 1); 40 | } 41 | 42 | const midpoint = Math.floor((2 * height - 1) / 2); 43 | let add; 44 | 45 | if(midpoint - row <= level.length && midpoint + row >= level.length){ 46 | add = '#'; 47 | } else { 48 | add = ' '; 49 | } 50 | 51 | pyramidsRecursive(height, row, level + add); 52 | 53 | } 54 | 55 | pyramidsRecursive(3); -------------------------------------------------------------------------------- /interviewcake/arrays/03-highestProductOf3.js: -------------------------------------------------------------------------------- 1 | // Given an array of integers, find the highest product you can get from three of the integers. 2 | // The input arrayOfInts will always have at least three integers. 3 | 4 | var integers = [40, 1, 3, 2, 22, 39, 1, -12]; // 34320 5 | var negatives = [ 2, -10, -10, 1, 3]; // 300 6 | 7 | console.log(highetProductOfThree(negatives)); 8 | 9 | function highetProductOfThree(integers){ 10 | var highestOf3 = integers[0] * integers[1] * integers[2]; 11 | 12 | var highestOf2 = integers[0] * integers[1]; 13 | var lowestOf2 = integers[0] * integers[1]; 14 | 15 | var highest = Math.max(integers[0], integers[1]); 16 | var lowest = Math.min(integers[0], integers[1]); 17 | 18 | for(var i = 2; i < integers.length; i++){ 19 | var current = integers[i]; 20 | 21 | // do we have new highest of 3? 22 | highestOf3 = Math.max( 23 | highestOf3, 24 | current * highestOf2, 25 | current * lowestOf2 26 | ); 27 | 28 | // new highest of 2? 29 | highestOf2 = Math.max( 30 | highestOf2, 31 | current * highest, 32 | current * lowest 33 | ); 34 | 35 | // new lowest of 2? 36 | lowestOf2 = Math.max( 37 | lowestOf2, 38 | current * highest, 39 | current * lowest 40 | ); 41 | 42 | // new highest? 43 | highest = Math.max(highest, current); 44 | 45 | // new lowest? 46 | lowest = Math.max(lowest, current); 47 | } 48 | 49 | return highestOf3; 50 | } 51 | 52 | 53 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/08_capitalize.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a function that accepts a string. The function should 3 | // capitalize the first letter of each word in the string then 4 | // return the capitalized string. 5 | // --- Examples 6 | // capitalize('a short sentence') --> 'A Short Sentence' 7 | // capitalize('a lazy fox') --> 'A Lazy Fox' 8 | // capitalize('look, it is working!') --> 'Look, It Is Working!' 9 | 10 | function capitalize(string){ 11 | return string.split(' ').map((word)=>{ 12 | return word.substr(0, 1).toUpperCase() + word.substr(1); 13 | }).join(' '); 14 | } 15 | 16 | 17 | // console.log(capitalize('a short sentence')); //'A Short Sentence' 18 | // console.log(capitalize('a lazy fox')); // 'A Lazy Fox' 19 | // console.log(capitalize('look, it is working!')); // 'Look, It Is Working!' 20 | 21 | 22 | function capitalizeSolution1(string){ 23 | if(string.length === 0) return ''; 24 | 25 | let result = string[0].toUpperCase(); 26 | 27 | for(let i = 1; i < string.length; i++){ 28 | if(result[i-1] === " "){ 29 | result += string[i].toUpperCase(); 30 | } else { 31 | result += string[i]; 32 | } 33 | } 34 | 35 | return result; 36 | } 37 | 38 | console.log(capitalizeSolution1('a short sentence')); //'A Short Sentence' 39 | console.log(capitalizeSolution1('a lazy fox')); // 'A Lazy Fox' 40 | console.log(capitalizeSolution1('look, it is working!')); // 'Look, It Is Working!' 41 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/12_spiral_matrix.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Write a function that accepts an integer N 3 | // and returns a NxN spiral matrix. 4 | // --- Examples 5 | // matrix(2) 6 | // [[undefined, undefined], 7 | // [undefined, undefined]] 8 | // matrix(3) 9 | // [[1, 2, 3], 10 | // [8, 9, 4], 11 | // [7, 6, 5]] 12 | // matrix(4) 13 | // [[1, 2, 3, 4], 14 | // [12, 13, 14, 5], 15 | // [11, 16, 15, 6], 16 | // [10, 9, 8, 7]] 17 | 18 | function matrix(n) { 19 | const results = []; 20 | 21 | for (let i = 0; i < n; i++) { 22 | results.push([]); 23 | } 24 | 25 | let counter = 1; 26 | let startColumn = 0; 27 | let endColumn = n - 1; 28 | let startRow = 0; 29 | let endRow = n - 1; 30 | while (startColumn <= endColumn && startRow <= endRow) { 31 | // Top row 32 | for (let i = startColumn; i <= endColumn; i++) { 33 | results[startRow][i] = counter; 34 | counter++; 35 | } 36 | startRow++; 37 | 38 | // Right column 39 | for (let i = startRow; i <= endRow; i++) { 40 | results[i][endColumn] = counter; 41 | counter++; 42 | } 43 | endColumn--; 44 | 45 | // Bottom row 46 | for (let i = endColumn; i >= startColumn; i--) { 47 | results[endRow][i] = counter; 48 | counter++; 49 | } 50 | endRow--; 51 | 52 | // start column 53 | for (let i = endRow; i >= startRow; i--) { 54 | results[i][startColumn] = counter; 55 | counter++; 56 | } 57 | startColumn++; 58 | } 59 | 60 | return results; 61 | } 62 | 63 | module.exports = matrix; -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/15_qfroms.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Implement a Queue datastructure using two stacks. 3 | // *Do not* create an array inside of the 'Queue' class. 4 | // Queue should implement the methods 'add', 'remove', and 'peek'. 5 | // For a reminder on what each method does, look back 6 | // at the Queue exercise. 7 | // --- Examples 8 | // const q = new Queue(); 9 | // q.add(1); 10 | // q.add(2); 11 | // q.peek(); // returns 1 12 | // q.remove(); // returns 1 13 | // q.remove(); // returns 2 14 | 15 | const Stack = require('./data_structures/stack'); 16 | 17 | class Queue { 18 | constructor(){ 19 | this.stack1 = new Stack(); 20 | this.stack2 = new Stack(); 21 | } 22 | 23 | add(item){ 24 | this.stack1.push(item); 25 | } 26 | 27 | remove(){ 28 | 29 | while(this.stack1.peek()){ 30 | this.stack2.push(this.stack1.pop()) 31 | } 32 | 33 | const toRemove = this.stack2.pop(); 34 | 35 | while(this.stack2.peek()){ 36 | this.stack1.push(this.stack2.pop()); 37 | } 38 | 39 | return toRemove; 40 | 41 | } 42 | 43 | peek(){ 44 | 45 | while(this.stack1.peek()){ 46 | this.stack2.push(this.stack1.pop()); 47 | } 48 | 49 | const toShow = this.stack2.peek(); 50 | 51 | while(this.stack2.peek()){ 52 | this.stack1.push(this.stack2.pop()); 53 | } 54 | 55 | return toShow; 56 | 57 | } 58 | } 59 | 60 | // const q = new Queue(); 61 | // q.add(1); 62 | // q.add(2); 63 | // console.log(q.peek()); // returns 1 64 | // console.log(q.remove()); // returns 1 65 | // console.log(q.remove()); // returns 2 66 | 67 | module.exports = Queue; -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/data_structures/trees.js: -------------------------------------------------------------------------------- 1 | 2 | class Node { 3 | constructor(data){ 4 | this.data = data; 5 | this.children = []; 6 | } 7 | 8 | add(data){ 9 | this.children.push(new Node(data)); 10 | } 11 | 12 | remove(data){ 13 | this.children = this.children.filter((node)=>{ 14 | return node.data !== data; 15 | }); 16 | } 17 | } 18 | 19 | class Tree { 20 | constructor(){ 21 | this.root = null; 22 | } 23 | 24 | breadthFirstTraverse(){ 25 | const queue = [this.root]; // first in, first out 26 | 27 | while(queue.length){ 28 | // remove first element from queue 29 | const first = queue.shift(); 30 | 31 | // log out the element 32 | console.log(first.data); 33 | 34 | // ES6 Spread syntax example: 35 | //=========================== 36 | // var parts = ['shoulders', 'knees']; 37 | // var lyrics = ['head', ...parts, 'and', 'toes']; 38 | // outputs: ["head", "shoulders", "knees", "and", "toes"] 39 | 40 | // add each element of children into the queue 41 | queue.push(...first.children); 42 | 43 | } 44 | 45 | } 46 | 47 | depthFirstTraverse(){ 48 | const stack = [this.root]; 49 | 50 | while(stack.length){ 51 | const first = stack.shift(); 52 | 53 | console.log(first.data); 54 | 55 | stack.unshift(...first.children); 56 | } 57 | 58 | } 59 | } 60 | 61 | // const t = new Tree(); 62 | // t.root= new Node('a'); 63 | // t.root.add('b'); 64 | // t.root.add('d'); 65 | // t.root.children[0].add('c'); 66 | 67 | 68 | // t.depthFirstTraverse(); 69 | 70 | module.exports = { Tree, Node }; -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/14_weave.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Implement the 'weave' function. Weave 3 | // receives two queues as arguments and combines the 4 | // contents of each into a new, third queue. 5 | // The third queue should contain the *alterating* content 6 | // of the two queues. The function should handle 7 | // queues of different lengths without inserting 8 | // 'undefined' into the new one. 9 | // *Do not* access the array inside of any queue, only 10 | // use the 'add', 'remove', and 'peek' functions. 11 | // --- Example 12 | // const queueOne = new Queue(); 13 | // queueOne.add(1); 14 | // queueOne.add(2); 15 | // const queueTwo = new Queue(); 16 | // queueTwo.add('Hi'); 17 | // queueTwo.add('There'); 18 | // const q = weave(queueOne, queueTwo); 19 | // q.remove() // 1 20 | // q.remove() // 'Hi' 21 | // q.remove() // 2 22 | // q.remove() // 'There' 23 | 24 | const Queue = require('./data_structures/queue'); 25 | 26 | function weave(sourceOne, sourceTwo) { 27 | const result = new Queue(); 28 | 29 | while(sourceOne.peek() || sourceTwo.peek()){ 30 | if(sourceOne.peek()){ 31 | result.add(sourceOne.peek()); 32 | sourceOne.remove(); 33 | } 34 | 35 | if(sourceTwo.peek()){ 36 | result.add(sourceTwo.peek()); 37 | sourceTwo.remove(); 38 | } 39 | } 40 | 41 | return result; 42 | } 43 | 44 | const queueOne = new Queue(); 45 | queueOne.add(1); 46 | queueOne.add(2); 47 | const queueTwo = new Queue(); 48 | queueTwo.add('Hi'); 49 | queueTwo.add('There'); 50 | const q = weave(queueOne, queueTwo); 51 | q.remove(); // 1 52 | q.remove() // 'Hi' 53 | q.remove() // 2 54 | q.remove() // 'There' 55 | 56 | module.exports = weave; -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/13_fib.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Print out the n-th entry in the fibonacci series. 3 | // The fibonacci series is an ordering of numbers where 4 | // each number is the sum of the preceeding two. 5 | // For example, the sequence 6 | // [0, 1, 1, 2, 3, 5, 8, 13, 21, 34] 7 | // forms the first ten entries of the fibonacci series. 8 | // Example: 9 | // fib(4) === 3 10 | 11 | 12 | // Memoization: 13 | // store the arguments of each 14 | // function call along with the result. 15 | // If function is called with the same 16 | // arguments return the precompiled result 17 | function fib(n){ 18 | if(n < 2){ 19 | return n; 20 | } 21 | 22 | return fib(n - 2) + fib(n - 1, {}); 23 | } 24 | 25 | function memoize(fn){ 26 | const cache = {}; 27 | 28 | return function(...args){ 29 | if(cache[args]){ 30 | return cache[args]; 31 | } 32 | 33 | const result = fn.apply(this, args); 34 | cache[args] = result; 35 | 36 | return result; 37 | } 38 | } 39 | 40 | fib = memoize(fib); 41 | 42 | // Recursive solution 43 | // runtime complexity: exponential (really bad) 44 | // for every increase in n we're going to get a dramatic increase in the number of function calls 45 | // function fib(n){ 46 | // if(n == 0) return 0; 47 | // if(n == 1) return 1; 48 | 49 | // return fib(n - 2) + fib(n - 1); 50 | // } 51 | 52 | // iterative solution 53 | // runtime complexity: linear 54 | // 55 | // function fib(n){ 56 | // const sequence = [0, 1]; 57 | 58 | // for(let i = 2; i <= n; i++){ 59 | // const entry = sequence[i - 2] + sequence[i - 1]; 60 | // sequence.push(entry); 61 | // } 62 | // return entry; 63 | // } 64 | 65 | console.log(fib(4)); 66 | console.log(fib(9)); -------------------------------------------------------------------------------- /practice/algorithms/binarySearch.js: -------------------------------------------------------------------------------- 1 | // Select the middle element and compare lower or higher 2 | 3 | // O(log n) 4 | 5 | /****** Iterative Solution *******/ 6 | 7 | /* Returns either the index of the location in the array, 8 | or -1 if the array did not contain the targetValue */ 9 | function doSearch(array, targetValue) { 10 | var min = 0; 11 | var max = array.length - 1; 12 | var guess; 13 | 14 | while(max >= min){ 15 | guess = Math.floor((min+max)/2); 16 | 17 | if(array[guess] === targetValue){ 18 | return guess; 19 | } else if(array[guess] < targetValue){ 20 | min = guess + 1; 21 | } else { 22 | max = guess - 1; 23 | } 24 | } 25 | return -1; 26 | }; 27 | 28 | var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 29 | 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]; 30 | var result = doSearchRecursive(primes, 73); 31 | console.log("Found prime at index " + result); 32 | 33 | 34 | 35 | /****** Recursive Solution (does not find index) *******/ 36 | 37 | /* Returns either the index of the location in the array, 38 | or -1 if the array did not contain the targetValue */ 39 | // function doSearch(array, targetValue) { 40 | // var min = 0; 41 | // var max = array.length - 1; 42 | 43 | // var guess = parseInt((min + max)/2, 10); 44 | 45 | // if(array[guess] === targetValue){ 46 | // return true; 47 | // } 48 | 49 | // if(array[guess] > targetValue){ 50 | // var newArr = array.slice(min, guess + 1); 51 | // return doSearchRecursive(newArr, targetValue); 52 | // } else if (array[guess] < targetValue){ 53 | // var newArr = array.slice(guess + 1, max); 54 | // return doSearchRecursive(newArr, targetValue); 55 | // } 56 | 57 | // return -1; 58 | // }; 59 | 60 | 61 | -------------------------------------------------------------------------------- /flexbox/navigation.html: -------------------------------------------------------------------------------- 1 |
2 | 19 |
20 | 21 | -------------------------------------------------------------------------------- /interviewcake/arrays/02-productOfOtherNumbers.js: -------------------------------------------------------------------------------- 1 | // You have an array of integers, and for each index you want 2 | // to find the product of every integer except the integer at that index. 3 | // given [1, 7, 3, 4] 4 | // returns [84, 12, 28, 21] 5 | 6 | // it is product of all other values 7 | // so [ 7*3*4, 1*3*4, 1*7*4, 1*7*3] 8 | 9 | // Do not use division in your solution. 10 | 11 | var nums = [10, 7, 3, 4]; // [84, 12, 28, 21] 12 | var nums2 = [2, 4, 10]; // 13 | 14 | var output = getProductsOfAllIntsExceptAtIndex(nums2); 15 | console.log(output); 16 | 17 | function getProductsOfAllIntsExceptAtIndex(intArray){ 18 | 19 | // product of all integers before each index 20 | var beforeIndexValues = []; 21 | 22 | var accumulator = 1; 23 | 24 | for (var i = 0; i < intArray.length; i++) { 25 | beforeIndexValues[i] = accumulator; 26 | accumulator *= intArray[i]; 27 | } 28 | 29 | var afterIndexValues = []; 30 | accumulator = 1; 31 | 32 | // product of all integers after each index 33 | for(var i = intArray.length - 1; i >= 0; i--){ 34 | afterIndexValues[i] = accumulator; 35 | accumulator *= intArray[i]; 36 | } 37 | 38 | // multiply them together 39 | return beforeIndexValues.map((num, i) => { 40 | return num * afterIndexValues[i]; 41 | }); 42 | } 43 | 44 | 45 | 46 | // brute force approach is to walk through the array and for each element 47 | // walk through the array again and multiply all integers besides the given 48 | // element and store that value in a new array. 49 | 50 | // function getProductsOfAllIntsExceptAtIndex(integers){ 51 | // var output = []; 52 | 53 | // for(var i = 0; i < integers.length; i++){ 54 | // var current = integers[0]; 55 | // var product = 1; 56 | 57 | // for(var j = 0; j < integers.length; j++){ 58 | // if(j !== i){ 59 | // product = product * integers[j]; 60 | // } 61 | // } 62 | // output.push(product); 63 | // } 64 | // return output; 65 | // } 66 | 67 | -------------------------------------------------------------------------------- /practice/readme.md: -------------------------------------------------------------------------------- 1 | JS Array Methods 2 | === 3 | 4 | ``` 5 | // Map: 6 | //=== 7 | // The map() method creates a new array with the results 8 | // of calling a provided function on every element in the calling array. 9 | 10 | // map(currentValue, index, array) 11 | 12 | var numbers = [1, 5, 10, 15]; 13 | var doubles = numbers.map(function(x) { 14 | return x * 2; 15 | }); 16 | // doubles is now [2, 10, 20, 30] 17 | // numbers is still [1, 5, 10, 15] 18 | 19 | var numbers = [1, 4, 9]; 20 | var roots = numbers.map(Math.sqrt); 21 | // roots is now [1, 2, 3] 22 | // numbers is still [1, 4, 9] 23 | 24 | 25 | // Reduce: 26 | //=== 27 | // The reduce() method applies a function against an accumulator and each element 28 | // in the array (from left to right) to reduce it to a single value. 29 | 30 | // arr.reduce(callback[, initialValue]) 31 | 32 | var total = [0, 1, 2, 3].reduce(function(sum, value, i) { 33 | return sum + value; 34 | }, 0); 35 | // total is 6 36 | 37 | var flattened = [[0, 1], [2, 3], [4, 5]].reduce(function(a, b, i) { 38 | return a.concat(b); 39 | }, []); 40 | // flattened is [0, 1, 2, 3, 4, 5] 41 | 42 | 43 | // Includes 44 | var myArray = [1, 2, 3, 4, 5]; 45 | myArray.includes(1) // true 46 | 47 | // filter 48 | 49 | // lastIndexOf 50 | 51 | // slice(begin, end) 52 | 53 | // some() 54 | 55 | // every() 56 | 57 | // toString() 58 | 59 | // join() 60 | 61 | // pop() 62 | 63 | // slice(begin, end) - does not modify original array 64 | 65 | // splice(start, deleteCount) - modifies original array 66 | 67 | // sort() - sort happens in place, no array copy made. will not sort numbers. You must run arr.sort(function(a, b){ return a-b; }) OR arr.sort((a,b)=> a-b) 68 | 69 | ``` 70 | 71 | 72 | // sum all elements in an array 73 | 74 | JS Number Methods 75 | === 76 | 77 | Number.isInteger(x) 78 | 79 | 80 | JS Set 81 | === 82 | 83 | JS String Methods 84 | === 85 | 86 | // charAt 87 | 88 | // toUpperCase 89 | 90 | // repeat 91 | 92 | // substr 93 | 94 | // substring 95 | 96 | // split 97 | 98 | // charCodeAt 99 | 100 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/06_array_chunking.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Given an array and chunk size, divide the array into many subarrays 3 | // where each subarray is of length size 4 | // --- Examples 5 | // chunk([1, 2, 3, 4], 2) --> [[ 1, 2], [3, 4]] 6 | // chunk([1, 2, 3, 4, 5], 2) --> [[ 1, 2], [3, 4], [5]] 7 | // chunk([1, 2, 3, 4, 5, 6, 7, 8], 3) --> [[ 1, 2, 3], [4, 5, 6], [7, 8]] 8 | // chunk([1, 2, 3, 4, 5], 4) --> [[ 1, 2, 3, 4], [5]] 9 | // chunk([1, 2, 3, 4, 5], 10) --> [[ 1, 2, 3, 4, 5]] 10 | 11 | function chunk(array, size) { 12 | let currentChunk = 0; 13 | let result = []; 14 | let chunk = []; 15 | 16 | for(var i = 0; i < array.length; i++){ 17 | if(currentChunk == size){ 18 | result.push(chunk); 19 | currentChunk = 0; 20 | chunk = []; 21 | } 22 | 23 | currentChunk++; 24 | chunk.push(array[i]); 25 | } 26 | 27 | if(chunk.length) result.push(chunk); 28 | 29 | return result; 30 | } 31 | 32 | 33 | function chunkSolution1(array, size){ 34 | // create empty array to hold all other arrays 35 | const chunked = []; 36 | 37 | for(let element of array){ 38 | // retrieve the last element in the chunked array 39 | const last = chunked[chunked.length - 1]; 40 | 41 | // if there is no last element or it's length is the size 42 | if(!last || last.length === size){ 43 | 44 | // add a new chunk with the current element 45 | chunked.push([element]); 46 | } else { 47 | // add the current element into the chunk 48 | last.push(element); 49 | } 50 | } 51 | 52 | return chunked; 53 | } 54 | 55 | 56 | // Rolling window with startIndex variable 57 | // Good practice for using Array.prototype.slice 58 | // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice 59 | function chunkSolution2(array, size){ 60 | let startIndex = 0; 61 | let output = []; 62 | 63 | while(startIndex < array.length){ 64 | 65 | output.push(array.slice(startIndex, startIndex + size)); 66 | 67 | startIndex += size; 68 | } 69 | 70 | return output; 71 | } 72 | 73 | 74 | 75 | console.log(chunkSolution2([1, 2, 3, 4], 2)); 76 | console.log(chunkSolution2([1, 2, 3, 4, 5, 6, 7, 8], 3)); 77 | console.log(chunkSolution2([1, 2, 3, 4, 5], 4)); 78 | -------------------------------------------------------------------------------- /interviewcake/arrays/01-appleStock.js: -------------------------------------------------------------------------------- 1 | // The indices are the time in minutes past trade opening time, which was 9:30am local time. 2 | // The values are the price in dollars of Apple stock at that time. 3 | 4 | // Write an efficient function that takes stockPricesYesterday and returns the 5 | // best profit I could have made from 1 purchase and 1 sale of 1 Apple stock yesterday. 6 | 7 | var stockPricesYesterday = [14, 7, 5, 8, 11, 4]; // 6 (buying for $5 and selling for $11) 8 | var stockPricesToday = [14, 7, 5, 3, 2, 1]; // -1 9 | var otherDay = [29, 54, 1, 3, 2, 32]; // 31 10 | var lastWeek = [3, 100, 1, 3, 2, 32]; // 97 11 | 12 | var profit = getMaxProfit(stockPricesToday); 13 | console.log(profit); 14 | 15 | // Description: 16 | //========= 17 | 18 | // A greedy algorithm iterates through problem space taking the optimal solution 19 | // so far. We're going to greedily walk through the array and track max profit and 20 | // lowest price so far. 21 | 22 | // for every price we check if we can get a better profit buying at minPrice 23 | // and selling at current price 24 | 25 | // we start by initializing minPrice as the first price 26 | // and maxProfit as the first profit we could get 27 | 28 | function getMaxProfit(prices){ 29 | var minPrice = prices[0]; 30 | var maxProfit = prices[1] - prices[0]; 31 | 32 | for(var i = 1; i < prices.length; i++){ 33 | var currentPrice = prices[i]; 34 | var potentialProfit = currentPrice - minPrice; 35 | 36 | if(maxProfit < potentialProfit){ 37 | maxProfit = potentialProfit; 38 | } 39 | 40 | if(currentPrice < minPrice){ 41 | minPrice = currentPrice; 42 | } 43 | } 44 | return maxProfit; 45 | } 46 | 47 | 48 | 49 | 50 | ////// brute force O(n^2) implementation: 51 | //========= 52 | 53 | // function getMaxProfit(prices){ 54 | // var profit, profits = []; 55 | 56 | // for(var i = 0; i < prices.length; i++){ 57 | // var bought = prices[i]; 58 | // var selling = prices.slice(i+1); 59 | // profit = prices[i + 1] - bought; 60 | 61 | // for(var j = 0; j < selling.length; j++){ 62 | // if((selling[j] - bought) > profit){ 63 | // profit = selling[j] - bought; 64 | // } 65 | // } 66 | 67 | // if(!isNaN(profit)) profits.push(profit); 68 | // } 69 | // profits.sort((a,b)=>a-b) 70 | // return profits[profits.length - 1]; 71 | // } 72 | 73 | 74 | 75 | 76 | 77 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/07_anagrams.js: -------------------------------------------------------------------------------- 1 | // --- Directions 2 | // Check to see if two provided strings are anagrams of eachother. 3 | // One string is an anagram of another if it uses the same characters 4 | // in the same quantity. Only consider characters, not spaces 5 | // or punctuation. Consider capital letters to be the same as lower case 6 | // --- Examples 7 | // anagrams('rail safety', 'fairy tales') --> True 8 | // anagrams('RAIL! SAFETY!', 'fairy tales') --> True 9 | // anagrams('Hi there', 'Bye there') --> False 10 | 11 | function anagrams(string1, string2){ 12 | let sorted1 = string1.replace(/[^\w]/g, '').toLowerCase().split('').sort().join(''); 13 | let sorted2 = string2.replace(/[^\w]/g, '').toLowerCase().split('').sort().join(''); 14 | 15 | return (sorted1 === sorted2); 16 | 17 | } 18 | 19 | // console.log(anagrams('rail safety', 'fairy tales')); // true 20 | // console.log(anagrams('RAIL! SAFETY!', 'fairy tales')); // true 21 | // console.log(anagrams('Hi there', 'Bye there')); // false 22 | 23 | // Regular Expressions: 24 | // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp 25 | // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions 26 | // string.replace(/[^\w]/g, "") --> removes any non-alphanumeric characters 27 | 28 | // Object.keys(obj).length --> gets the number of keys in a JS object 29 | 30 | 31 | function anagramsSolution1(string1, string2){ 32 | let obj1 = {}, 33 | obj2 = {}, 34 | s1 = string1.replace(/[^\w]/g, '').toLowerCase().split(''); 35 | s2 = string2.replace(/[^\w]/g, '').toLowerCase().split(''); 36 | 37 | if(s1.length !== s2.length) return false; 38 | 39 | s1.forEach((letter)=>{ 40 | obj1[letter] = (obj1[letter]) ? obj1[letter] + 1 : 1; 41 | }); 42 | 43 | s2.forEach((letter)=>{ 44 | obj2[letter] = (obj2[letter]) ? obj2[letter] + 1 : 1; 45 | }); 46 | 47 | for(var char in obj1){ 48 | if(obj1[char] !== obj2[char]) return false; 49 | } 50 | 51 | return true; 52 | } 53 | 54 | 55 | 56 | console.log(anagramsSolution1('rail safety', 'fairy tales')); //True 57 | console.log(anagramsSolution1('RAIL! SAFETY!', 'fairy tales')); // True 58 | console.log(anagramsSolution1('Hi there', 'Bye there')); // False 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | -------------------------------------------------------------------------------- /flexbox/style.css: -------------------------------------------------------------------------------- 1 | /* CSS Normalize */ 2 | article,aside,details,figcaption,figure,footer,header,hgroup,nav,section,summary{display:block;}audio,canvas,video{display:inline-block;}audio:not([controls]){display:none;height:0;}[hidden]{display:none;}html{font-family:sans-serif;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;}a:focus{outline:thin dotted;}a:active,a:hover{outline:0;}h1{font-size:2em;}abbr[title]{border-bottom:1px dotted;}b,strong{font-weight:700;}dfn{font-style:italic;}mark{background:#ff0;color:#000;}code,kbd,pre,samp{font-family:monospace, serif;font-size:1em;}pre{white-space:pre-wrap;word-wrap:break-word;}q{quotes:\201C \201D \2018 \2019;}small{font-size:80%;}sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline;}sup{top:-.5em;}sub{bottom:-.25em;}img{border:0;}svg:not(:root){overflow:hidden;}fieldset{border:1px solid silver;margin:0 2px;padding:.35em .625em .75em;}button,input,select,textarea{font-family:inherit;font-size:100%;margin:0;}button,input{line-height:normal;}button,html input[type=button],/* 1 */ 3 | input[type=reset],input[type=submit]{-webkit-appearance:button;cursor:pointer;}button[disabled],input[disabled]{cursor:default;}input[type=checkbox],input[type=radio]{box-sizing:border-box;padding:0;}input[type=search]{-webkit-appearance:textfield;-moz-box-sizing:content-box;-webkit-box-sizing:content-box;box-sizing:content-box;}input[type=search]::-webkit-search-cancel-button,input[type=search]::-webkit-search-decoration{-webkit-appearance:none;}textarea{overflow:auto;vertical-align:top;}table{border-collapse:collapse;border-spacing:0;}body,figure{margin:0;}legend,button::-moz-focus-inner,input::-moz-focus-inner{border:0;padding:0;} 4 | 5 | /* Box-sizing border-box */ 6 | * { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; } 7 | 8 | 9 | /* Some default styles to make each box visible */ 10 | .box { 11 | color:white; 12 | font-size: 100px; 13 | text-align: center; 14 | text-shadow:4px 4px 0 rgba(0,0,0,0.1); 15 | padding:10px; 16 | } 17 | 18 | /* Colours for each box */ 19 | .box1 { background:#1abc9c;} 20 | .box2 { background:#3498db;} 21 | .box3 { background:#9b59b6;} 22 | .box4 { background:#34495e;} 23 | .box5 { background:#f1c40f;} 24 | .box6 { background:#e67e22;} 25 | .box7 { background:#e74c3c;} 26 | .box8 { background:#bdc3c7;} 27 | .box9 { background:#2ecc71;} 28 | .box10 { background:#16a085;} 29 | 30 | 31 | /* We start writing out flexbox here. The above is just page setup */ 32 | .container { 33 | display:flex; 34 | border:10px solid goldenrod; 35 | height:100vh; 36 | } -------------------------------------------------------------------------------- /data-structures/curriculum.md: -------------------------------------------------------------------------------- 1 | # Interview Prep Curriculum 2 | 3 | This is meant to shore up computer science fundamentals for the self taught programmer. 4 | 5 | 6 | ## 0. Getting set up 7 | 8 | - Practical Algorithms and Data Structures from Bradfield Computer Science: https://bradfieldcs.com/algos/ 9 | - Read [The Big Picture](https://bradfieldcs.com/algos/analysis/introduction/) 10 | 11 | - Join Exercism.io and join the track for your language of choice. In my case this means joining the [PHP](https://exercism.io/my/tracks/php) and [Javascript](https://exercism.io/my/tracks/javascript) tracks. 12 | 13 | 14 | ## 1. Time and space complexity: Big O Notation 15 | 16 | **Resources:** 17 | 18 | - Bradfield CS: [Big O Notation](https://bradfieldcs.com/algos/analysis/big-o-notation/) 19 | 20 | - Introduction to Big O notation from Rithm School [Computer Science Fundamentals course](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/introduction-to-big-o-notation) 21 | 22 | - Asymptotic notation section of [Khan Academy Algorithms course](https://www.khanacademy.org/computing/computer-science/algorithms/asymptotic-notation/a/asymptotic-notation) 23 | 24 | 25 | ## 2. Data Structures I 26 | 27 | ### Stacks 28 | 29 | - Bradfield CS: [Stacks](https://bradfieldcs.com/algos/stacks/introduction/) 30 | 31 | ### Queues 32 | 33 | - Bradfield CS: [Queues](https://bradfieldcs.com/algos/queues/introduction/) 34 | 35 | ### Lists 36 | 37 | - Bradfield CS: [Lists](https://bradfieldcs.com/algos/lists/introduction/) 38 | 39 | 40 | ## 3. Recursion 41 | 42 | - Bradfield CS: [Recursion](https://bradfieldcs.com/algos/recursion/introduction/) 43 | 44 | - Rithm School: [Recursion](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/introduction-to-recursion) 45 | 46 | 47 | ## 4. Searching and Sorting 48 | 49 | - Bradfield CS: [Searching](https://bradfieldcs.com/algos/searching/searching/) 50 | 51 | - Rithm School: [Searching](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/searching-algorithms), [Sorting](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/basic-sorting-algorithms), [Intermediate Sorting](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/intermediate-sorting-algorithms) 52 | 53 | 54 | ## 5. Data Structures II 55 | 56 | ### Trees 57 | 58 | - Bradfield CS: [Trees](https://bradfieldcs.com/algos/trees/introduction/) 59 | 60 | ### Graphs 61 | 62 | - Bradfield CS: [Graphs](https://bradfieldcs.com/algos/graphs/introduction/) 63 | 64 | - Rithm School: [Graphs](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/introduction-to-graphs) 65 | 66 | ### Hash Map 67 | 68 | - Rithm School: [Hash Map / Hash Table](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/introduction-to-hash-tables) 69 | 70 | ## 6. Dynamic Programming 71 | 72 | - Rithm School: [Dynamic Programming](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/dynamic-programming) 73 | 74 | 75 | -------------------------------------------------------------------------------- /udemy-interview-bootcamp-course/data_structures/linked_list.js: -------------------------------------------------------------------------------- 1 | 2 | class Node { 3 | constructor(data, node = null){ 4 | this.data = data; 5 | this.next = node; 6 | } 7 | } 8 | 9 | class LinkedList { 10 | constructor(){ 11 | this.head = null 12 | } 13 | 14 | insertFirst(data){ 15 | this.head = new Node(data, this.head); 16 | } 17 | 18 | size(){ 19 | let size = 0, pointer = this.head; 20 | 21 | while(pointer){ 22 | pointer = pointer.next; 23 | size++; 24 | } 25 | 26 | return size; 27 | } 28 | 29 | getFirst(){ 30 | return this.head; 31 | } 32 | 33 | getLast(){ 34 | let last = this.head; 35 | if(!last){ 36 | return last; 37 | } 38 | 39 | while(last){ 40 | if(!last.next){ 41 | return last; 42 | } 43 | last = last.next; 44 | } 45 | } 46 | 47 | clear(){ 48 | this.head = null; 49 | } 50 | 51 | removeFirst(){ 52 | if(!this.head){ 53 | return; 54 | } 55 | 56 | this.head = this.head.next; 57 | } 58 | 59 | removeLast(){ 60 | // if empty list, nothing to remove 61 | if(!this.head){ 62 | return; 63 | } 64 | 65 | // if one node, remove it 66 | if(!this.head.next){ 67 | this.head = null; 68 | } 69 | 70 | let previous = this.head; 71 | let node = this.head.next; 72 | 73 | // if three nodes continue down the list 74 | while(node.next){ 75 | previous = node; 76 | node = node.next; 77 | } 78 | 79 | // remove pointer to the last node 80 | previous.next = null; 81 | } 82 | 83 | insertLast(data){ 84 | let last = this.getLast(); 85 | 86 | if(last){ 87 | last.next = new Node(data); 88 | } else { 89 | this.head = new Node(data); 90 | } 91 | } 92 | 93 | getAt(index){ 94 | let node = this.head, counter = 0; 95 | 96 | if(!node){ 97 | return null; 98 | } 99 | 100 | while(node){ 101 | if(counter === index){ 102 | return node; 103 | } 104 | counter++; 105 | node = node.next; 106 | } 107 | 108 | // index was out of bounds 109 | return null; 110 | } 111 | 112 | // todo: review methods below 113 | removeAt(index){ 114 | if(!this.head){ 115 | return; 116 | } 117 | 118 | if(index === 0){ 119 | this.head = this.head.next; 120 | return; 121 | } 122 | 123 | const previous = this.getAt(index - 1); 124 | if(!previous || !previous.next){ 125 | return; 126 | } 127 | 128 | previous.next = previous.next.next; 129 | 130 | } 131 | 132 | insertAt(data, index){ 133 | if(!this.head){ 134 | this.head = new Node(data); 135 | return; 136 | } 137 | 138 | if(index === 0){ 139 | this.head = new Node(data, this.head); 140 | return; 141 | } 142 | 143 | const previous = this.getAt(index - 1) || this.getLast(); 144 | const node = new Node(data, previous.next); 145 | previous.next = node; 146 | } 147 | 148 | forEach(fn){ 149 | let node = this.head; 150 | let counter = 0; 151 | 152 | while(node){ 153 | fn(node, counter); 154 | node = node.next; 155 | counter++; 156 | } 157 | } 158 | 159 | } 160 | 161 | module.exports = { Node, LinkedList }; -------------------------------------------------------------------------------- /hackerrank/readme.md: -------------------------------------------------------------------------------- 1 | **Robot Paths** 2 | 3 | A robot located at the top left corner of a 5x5 grid is trying to reach the bottom right corner. The robot can move either up, down, left, or right, but cannot visit the same spot twice. How many possible unique paths are there to the bottom right corner? 4 | 5 | Make your solution work for a grid of any size. 6 | 7 | 8 | ### From HackerRank UI Engineer Challenge: 9 | 10 | **Braces** 11 | 12 | Braces in a string are considered to be balanced if the following criteria are met: 13 | For every opening brace (i.e., (, {, or [), there is a matching closing brace (i.e., ), }, or ]) of the same type (i.e., ( matches ), { matches }, and [ matches ]). An opening brace must appear before (to the left of) its matching closing brace. For example, ]{}[ is not balanced. 14 | No unmatched braces lie between some pair of matched braces. For example, ({[]}) is balanced, but {[}] and [{)] are not balanced. 15 | 16 | Complete the braces function in the editor below. It has one parameter: an array of n strings, values. For each string in values, it must determine if all the braces in the string are balanced. The function must return an array of strings where the string at each index i (where 0 ≤ i < n) denotes whether or not all the braces in string valuesi were balanced. If yes, then index i in the return array must contain the string YES; otherwise, index i in the return array must contain the string NO. 17 | 18 | **Todo List Mark** 19 | 20 | Books on personal productivity emphasize the importance of using a To-Do-List. This list helps you organize your daily tasks and monitor your performance over time. Your task is to make it available online. 21 | 22 | You are provided with some code stubs which implement a limited functionality for this app. 23 | Modify the code to enable the following operation: 24 | 25 | Mark an item as complete. 26 | 27 | You can store the data in Javascript objects or in local storage. 28 | 29 | Please Note: 30 | This question is graded manually by a tech manager. So you can be as creative as you want to be. 31 | You can test your code by pressing the "Render" button below. 32 | You can use any library/framework to create this. 33 | You are free to design the UX of your choice. 34 | 35 | **Javascript Assignment** 36 | 37 | Consider the following JavaScript code snippet: 38 | 39 | ``` 40 | function foo () { 41 | return 5 42 | } 43 | ``` 44 | What will the code let myVar = foo; do? 45 | 46 | Assign the integer value 5 to the variable myVar 47 | 48 | Assign a reference to the foo function to the variable myVar 49 | 50 | Throw an exception 51 | 52 | Nothing 53 | 54 | **CSS Resize** 55 | 56 | Consider the following CSS3 code: 57 | 58 | ``` 59 | div { 60 | border: 2px solid; 61 | resize: horizontal; 62 | overflow: auto; 63 | } 64 | ``` 65 | 66 | What is the job of resize attribute here? 67 | To make the div element resizable by the user. 68 | To make the div element resizable by the browser. 69 | To increase the horizontal padding. 70 | To make the div element resizable by javascript. 71 | 72 | 73 | 74 | **Which of the following code snippet append an element value at the end of the array, arr?** 75 | 76 | arr[arr.length + 1] = value 77 | 78 | arr[arr.length] = value 79 | 80 | arr[arr.length - 1] = value 81 | 82 | arr = arr + value 83 | 84 | 85 | **Consider the two functions below. Will they return the same thing? Select the most accurate response.** 86 | ``` 87 | function foo1() 88 | { 89 | return { 90 | bar: "hello" 91 | }; 92 | } 93 | 94 | function foo2() 95 | { 96 | return 97 | { 98 | bar: "hello" 99 | }; 100 | } 101 | ``` 102 | 103 | -------------------------------------------------------------------------------- /sql/02-relational-queries.sql: -------------------------------------------------------------------------------- 1 | /* 2 | 3 | Covers joins and multi table queries. I also suggest watching 4 | this laracast episode: https://laracasts.com/lessons/understanding-joins 5 | 6 | */ 7 | 8 | /* Student grades */ 9 | 10 | CREATE TABLE students (id INTEGER PRIMARY KEY, 11 | first_name TEXT, 12 | last_name TEXT, 13 | email TEXT, 14 | phone TEXT, 15 | birthdate TEXT, 16 | buddy_id INTEGER); 17 | 18 | INSERT INTO students (first_name, last_name, email, phone, birthdate) 19 | VALUES ("Peter", "Rabbit", "peter@rabbit.com", "555-6666", "2002-06-24", 2); 20 | INSERT INTO students (first_name, last_name, email, phone, birthdate) 21 | VALUES ("Alice", "Wonderland", "alice@wonderland.com", "555-4444", "2002-07-04", 1); 22 | INSERT INTO students 23 | VALUES (3, "Aladdin", "Lampland", "aladdin@lampland.com", "555-3333", "2001-05-10", 4); 24 | INSERT INTO students 25 | VALUES (4, "Simba", "Kingston", "simba@kingston.com", "555-1111", "2001-12-24", 3); 26 | 27 | CREATE TABLE student_grades (id INTEGER PRIMARY KEY, 28 | student_id INTEGER, 29 | test TEXT, 30 | grade INTEGER); 31 | 32 | INSERT INTO student_grades (student_id, test, grade) 33 | VALUES (1, "Nutrition", 95); 34 | INSERT INTO student_grades (student_id, test, grade) 35 | VALUES (2, "Nutrition", 92); 36 | INSERT INTO student_grades (student_id, test, grade) 37 | VALUES (1, "Chemistry", 85); 38 | INSERT INTO student_grades (student_id, test, grade) 39 | VALUES (2, "Chemistry", 95); 40 | 41 | SELECT * FROM student_grades; 42 | 43 | /* cross join */ 44 | SELECT * FROM student_grades, students; 45 | 46 | /* implicit inner join */ 47 | SELECT * FROM student_grades, students 48 | WHERE student_grades.student_id = students.id; 49 | 50 | /* explicit inner join - JOIN */ 51 | SELECT students.first_name, students.last_name, students.email, student_grades.test, student_grades.grade FROM students 52 | JOIN student_grades 53 | ON students.id = student_grades.student_id 54 | WHERE grade > 90; 55 | 56 | create table student_projects (id integer primary key, student_id integer, title text); 57 | 58 | insert into student_projects (student_id, title) values (1, 'Carrotapault'); 59 | 60 | /* inner join only creates records for matches between the two tables */ 61 | select students.first_name, students.last_name, student_projects.title 62 | from students 63 | join student_projects 64 | on students.id = student_projects.student_id; 65 | 66 | /* outer join - list of all students and their projects, regardless if they have a project or not */ 67 | select students.first_name, students.last_name, student_projects.title 68 | from students 69 | left outer join student_projects /* outer means to retain the rows even if there is no match */ 70 | on students.id = student_projects.student_id; 71 | 72 | /* self join - ids are in the same table */ 73 | select students.first_name, students.last_name, buddies.email as buddy_email 74 | from students 75 | join students buddies /* alias for table */ 76 | on students.buddy_id = buddies.id; 77 | 78 | /* Bobby's hobbies */ 79 | 80 | /* display a table of people and their hobbies */ 81 | select persons.name, hobbies.name from hobbies join persons on persons.id = hobbies.person_id; 82 | 83 | /* display only Bobby's hobbies */ 84 | select persons.name, hobbies.name 85 | from persons join hobbies 86 | where persons.name = 'Bobby McBobbyFace' and hobbies.person_id = persons.id; 87 | 88 | /* Customers' orders */ 89 | 90 | CREATE TABLE customers ( 91 | id INTEGER PRIMARY KEY AUTOINCREMENT, 92 | name TEXT, 93 | email TEXT); 94 | 95 | INSERT INTO customers (name, email) VALUES ("Doctor Who", "doctorwho@timelords.com"); 96 | INSERT INTO customers (name, email) VALUES ("Harry Potter", "harry@potter.com"); 97 | INSERT INTO customers (name, email) VALUES ("Captain Awesome", "captain@awesome.com"); 98 | 99 | CREATE TABLE orders ( 100 | id INTEGER PRIMARY KEY AUTOINCREMENT, 101 | customer_id INTEGER, 102 | item TEXT, 103 | price REAL); 104 | 105 | INSERT INTO orders (customer_id, item, price) 106 | VALUES (1, "Sonic Screwdriver", 1000.00); 107 | INSERT INTO orders (customer_id, item, price) 108 | VALUES (2, "High Quality Broomstick", 40.00); 109 | INSERT INTO orders (customer_id, item, price) 110 | VALUES (1, "TARDIS", 1000000.00); 111 | 112 | /* select all 'customers' and their orders even if they have not ordered before */ 113 | select customers.name, customers.email, orders.item, orders.price 114 | from customers 115 | left outer join orders 116 | on customers.id = orders.customer_id; 117 | 118 | /* show a list of all customers and their total order volume */ 119 | select customers.name, customers.email, sum(orders.price) as total_spending 120 | from customers 121 | left outer join orders 122 | on customers.id = orders.customer_id 123 | group by customers.email 124 | order by total_spending desc; 125 | 126 | /* Harry Potter sequels - self join */ 127 | 128 | select movies.title, sequel.title 129 | from movies 130 | left outer join movies sequel 131 | on movies.sequel_id = sequel.id; 132 | 133 | /* Friendbook */ 134 | 135 | select persons.fullname, hobbies.name 136 | from persons 137 | join hobbies 138 | on persons.id = hobbies.person_id; 139 | 140 | select persons1.fullname, persons2.fullname 141 | from friends 142 | join persons persons1 143 | on persons1.id = friends.person1_id 144 | join persons persons2 145 | on persons2.id = friends.person2_id; 146 | 147 | /* 148 | Famous persons project 149 | Movie stars: What movies are they in? Are they married to each other? 150 | Singers: What songs did they write? Where are they from? 151 | Authors: What books did they write? 152 | Fictional characters: How are they related to other characters? What books do they show up in? 153 | */ 154 | 155 | 156 | 157 | /* 158 | Query planning and optimization: parse -> optimize -> execute 159 | 160 | query tuning with a sql profiler. manual optimization to improve the execution plan. 161 | 162 | create indexes makes repeated queries more efficient. 163 | 164 | query planner for sqlite: https://www.sqlite.org/queryplanner.html 165 | 166 | 167 | */ 168 | 169 | 170 | 171 | 172 | 173 | 174 | 175 | 176 | 177 | -------------------------------------------------------------------------------- /practice/recursion.js: -------------------------------------------------------------------------------- 1 | // Write a function called `sumRange`. It will take a number and return 2 | //the sum of all numbers from 1 up to the number passed in. 3 | 4 | // sumRange(3) returns 6, since 1 + 2 + 3 = 6. 5 | 6 | var output = sumRange(3) 7 | // console.log(output); 8 | 9 | function sumRange(num){ 10 | if(num == 1) return 1; 11 | 12 | return num + sumRange(num - 1); 13 | } 14 | 15 | 16 | // Write a function called `power` which takes in a base and an exponent. If 17 | // the exponent is 0, return 1. 18 | 19 | // You can think of it in terms of this example: 20 | // 2^4 = 2 * 2^3; 21 | // 2^3 = 2 * 2^2; 22 | // 2^2 = 2 * 2^1; 23 | // 2^1 = 2 * 2^0; // once our exponent is 0 we KNOW that the value is always 1! 24 | 25 | // console.log(power(2, 4)); 26 | // console.log(power(2, 3)); 27 | // console.log(power(2, 2)); 28 | // console.log(power(2, 1)); 29 | // console.log(power(2, 0)); 30 | 31 | function power(base, exponent){ 32 | if(exponent == 0) return 1; 33 | return base * power(base, exponent - 1); 34 | } 35 | 36 | 37 | // Write a function that returns the `factorial` of a number. As a quick refresher, 38 | // a factorial of a number is the result of that number multiplied by the number 39 | // before it, and the number before that number, and so on, until you reach 1. 40 | // The factorial of 1 is just 1. For example: 41 | 42 | factorial(5); // 5 * 4 * 3 * 2 * 1 === 120 43 | 44 | function factorial(num){ 45 | if(num == 1) return 1; 46 | 47 | return num * factorial(num - 1); // pending multiplier 48 | } 49 | 50 | 51 | // Write a function called `all` which accepts an array and a callback and returns 52 | // true if every value in the array returns true when passed as parameter to the 53 | // callback function 54 | 55 | var allAreLessThanSeven = all([1,2,9], function(num){ 56 | return num < 7; 57 | }); 58 | 59 | console.log(allAreLessThanSeven); 60 | 61 | function all(array, callback){ 62 | var copy = copy || array.slice(); // shallow copies array 63 | 64 | if(copy.length === 0) return true; 65 | 66 | if(callback(copy[0])){ 67 | copy.shift(); // remove first element from array 68 | return all(copy, callback); 69 | } else { 70 | return false; 71 | } 72 | } 73 | 74 | 75 | // Write a function called productOfArray which takes in an array of numbers 76 | // and returns the product of them all 77 | 78 | var six = productOfArray([1,2,3]) // 6 79 | var sixty = productOfArray([1,2,3,10]) // 60 80 | 81 | // console.log(six, sixty); 82 | 83 | function productOfArray(array){ 84 | if(array.length === 0) return 1; 85 | 86 | return array.shift() * productOfArray(array); 87 | } 88 | 89 | 90 | // Write a function called `contains` that searches for a value in a nested object. 91 | // It returns true if the object contains that value. 92 | 93 | var nestedObject = { 94 | data: { 95 | info: { 96 | stuff: { 97 | thing: { 98 | moreStuff: { 99 | magicNumber: 44, 100 | something: 'foo2' 101 | } 102 | } 103 | } 104 | } 105 | } 106 | } 107 | 108 | let hasIt = contains(nestedObject, 44); // true 109 | let doesntHaveIt = contains(nestedObject, "foo"); // false 110 | 111 | // console.log(hasIt, doesntHaveIt); 112 | 113 | function contains(obj, value){ 114 | for(var key in obj){ 115 | if(typeof obj[key] === 'object'){ 116 | return contains(obj[key], value); 117 | } 118 | 119 | if (obj[key] === value){ 120 | return true; 121 | } 122 | } 123 | return false; 124 | } 125 | 126 | 127 | // Given a multi-dimensional integer array, return the total number of integers 128 | // stored inside this array 129 | 130 | var seven = totalIntegers([[[5], 3], 0, 2, ['foo'], [], [4, [5, 6]]]); // 7 131 | // console.log(seven); 132 | 133 | function totalIntegers(array){ 134 | if(array.length === 0) return 0; 135 | 136 | let total = 0; 137 | let first = array.shift(); 138 | 139 | if (Array.isArray(first)){ 140 | total += totalIntegers(first); 141 | } else if (Number.isInteger(first)) { 142 | total += 1; 143 | } 144 | 145 | return total + totalIntegers(array); 146 | } 147 | 148 | 149 | // Write a function that sums squares of numbers in list that may contain more lists 150 | 151 | var l = [1,2,3]; 152 | // console.log(SumSquares(l)); // 14 153 | 154 | l = [[1,2],3]; 155 | // console.log(SumSquares(l)); // 14 156 | 157 | l = [[[[[[[[[1]]]]]]]]] 158 | // console.log(SumSquares(l)); // 1 159 | 160 | l = [10,[[10],10],[10]] 161 | // console.log(SumSquares(l)); // 400 162 | 163 | function SumSquares(array){ 164 | if(array.length === 0) return 0; 165 | let total = 0; 166 | 167 | for(let i = 0; i < array.length; i++){ 168 | if(Array.isArray(array[i])){ 169 | total += SumSquares(array[i]); 170 | } else { 171 | total += array[i] * array[i]; 172 | } 173 | 174 | } 175 | return total; 176 | } 177 | 178 | 179 | // The function should return an array containing repetitions of the number argument. 180 | // For instance, replicate(3, 5) should return [5,5,5]. 181 | // If the times argument is negative, return an empty array. 182 | 183 | // console.log(replicate(3, 5)) // [5, 5, 5] 184 | // console.log(replicate(1, 69)) // [69] 185 | // console.log(replicate(-2, 6)) // [] 186 | 187 | function replicate(times, number){ 188 | if(times <= 0) return []; 189 | 190 | return [number].concat(replicate(times - 1, number)); 191 | } 192 | 193 | 194 | // BONUS 195 | //======= 196 | 197 | // Write a function called search that finds a value in an array and returns the index 198 | // where the value is at. If the value is not found, the function should return negative 1. 199 | 200 | // search([1,2,3,4,5],5) // 4 201 | // search([1,2,3,4,5],15) // -1 202 | 203 | 204 | // Refactor your search function to use a faster algorithm called binary search 205 | // https://www.youtube.com/watch?v=JQhciTuD3E8 206 | 207 | // binarySearch([1,2,3,4,5],5) // 4 208 | // binarySearch([1,2,3,4,5],15) // -1 209 | 210 | 211 | // Write a function called stringifyNumbers which takes in an object and finds all of the 212 | // values which are numbers and converts them to strings. 213 | 214 | var obj = { 215 | num: 1, 216 | test: [], 217 | data: { 218 | val: 4, 219 | info: { 220 | isRight: true, 221 | random: 66 222 | } 223 | } 224 | } 225 | 226 | // stringifyNumbers(obj) 227 | /*/ 228 | Output: 229 | { 230 | num: "1", 231 | test: [], 232 | data: { 233 | val: "4", 234 | info: { 235 | isRight: true, 236 | random: "66" 237 | } 238 | } 239 | } 240 | /*/ -------------------------------------------------------------------------------- /sql/01-sql-queries.sql: -------------------------------------------------------------------------------- 1 | /****** 2 | 3 | Khan Academy SQL course exercises 4 | 5 | https://www.khanacademy.org/computing/computer-programming/sql 6 | 7 | ******/ 8 | 9 | /* Books table */ 10 | 11 | CREATE TABLE books ( 12 | id integer PRIMARY key, 13 | name text, 14 | rating integer 15 | ); 16 | 17 | insert into books values (1, 'Harry Potter', 5); 18 | insert into books values (2, 'Chronicles of Narnia', 4); 19 | insert into books values (3, 'The Martian', null); 20 | 21 | 22 | /* Groceries table */ 23 | 24 | SELECT * FROM groceries WHERE aisle > 5 ORDER BY aisle; 25 | 26 | SELECT aisle, SUM(quantity) FROM groceries GROUP BY aisle; 27 | 28 | /* Online store */ 29 | 30 | create table bikes ( 31 | id integer primary key, 32 | name text, 33 | quantity integer, 34 | price numeric, 35 | category text 36 | ); 37 | 38 | insert into bikes values (1, 'Nimbus 2000', 10, 500.00, 'Mountain'); 39 | insert into bikes values (2, 'Firebolt', 5, 599.99, 'Racing'); 40 | insert into bikes values (3, 'RoadRacer', 1, 445.50, 'Racing'); 41 | insert into bikes values (4, 'MountainClimber', 6, 330.00, 'Mountain'); 42 | insert into bikes values (5, 'Beach Cruiser', 12, 220, 'Cruiser'); 43 | 44 | select category from bikes group by category order by quantity desc; 45 | 46 | select * from bikes where category = 'Mountain' order by price desc; 47 | select * from bikes where category = 'Racing' order by price desc; 48 | select * from bikes where category = 'Cruiser' order by price desc; 49 | 50 | select sum(quantity) from bikes; 51 | 52 | /* Karaoke selector */ 53 | 54 | select title from songs; 55 | select title from songs where released > 1990 or mood = 'epic'; 56 | select title from songs where released > 1990 and mood = 'epic' and duration < 240; 57 | 58 | /* Exercise logs */ 59 | 60 | create table exercise_logs ( 61 | id integer primary key autoincrement, 62 | type, text, minutes integer, 63 | calories integer, 64 | heart_rate integer 65 | ); 66 | create table drs_favorites ( 67 | id integer primary key, 68 | type text, 69 | reason text 70 | ); 71 | 72 | insert into exercise_logs(type, minutes, calories, heart_rate) values ('biking', 30, 100, 110); 73 | insert into drs_favorites(type, reason) values ('biking', 'improves endurance and flexibility.'); 74 | 75 | /* subquery - selects all activities that the user did that are recommended by doctor for cardio health */ 76 | select * from exercise_logs where type in (select type from drs_favorites where reason like "%cardiovascular%"); 77 | 78 | /* table of all types of activity and the total amount of calories burned by doing that activity */ 79 | select type, sum(calories) as total_calories from exercise_logs group by type; 80 | 81 | select type, sum(calories) as total_calories 82 | from exercise_logs 83 | group by type 84 | having total_calories > 150; /* having applies to the grouped condition */ 85 | 86 | /* 50-90% of max heart rate for activity */ 87 | select count(*) from exercise_logs 88 | where heart_rate >= round(.5 * (220 -30)) 89 | and heart_rate <= round(.9 * (220 - 30)); 90 | 91 | /* add column for activity's target heart rate status */ 92 | select type, heart_rate, 93 | case 94 | when heart_rate > 220 - 30 then 'above max' 95 | when heart_rate > round(.9 * (220 - 30)) then 'above target' 96 | when heart_rate > round(.5 * (220 - 30)) then 'within target' 97 | else 'below target' 98 | end as 'heart_rate_zone' 99 | from exercise_logs; 100 | 101 | /* Group the count of exercises by each heart rate zone */ 102 | select count(*), 103 | case 104 | when heart_rate > 220 - 30 then 'above max' 105 | when heart_rate > round(.9 * (220 - 30)) then 'above target' 106 | when heart_rate > round(.5 * (220 - 30)) then 'within target' 107 | else 'below target' 108 | end as 'heart_rate_zone' 109 | from exercise_logs 110 | group by heart_rate_zone; 111 | 112 | /* Playlist maker */ 113 | 114 | select title from songs where artist in (select name from artists where genre = 'Pop'); 115 | 116 | /* Wordiest author */ 117 | 118 | /* from books, author that has written more than a million words */ 119 | select author, sum(words) as total_words from books group by author having total_words > 1000000; 120 | 121 | /* author whose average book is over 150,000 words */ 122 | select author, avg(words) as avg_words from books group by author having avg_words > 150000; 123 | 124 | /* Gradebook */ 125 | 126 | CREATE TABLE student_grades ( 127 | id INTEGER PRIMARY KEY AUTOINCREMENT, 128 | name TEXT, 129 | number_grade INTEGER, 130 | fraction_completed REAL); 131 | 132 | INSERT INTO student_grades (name, number_grade, fraction_completed) 133 | VALUES ("Winston", 90, 0.805); 134 | INSERT INTO student_grades (name, number_grade, fraction_completed) 135 | VALUES ("Winnefer", 95, 0.901); 136 | INSERT INTO student_grades (name, number_grade, fraction_completed) 137 | VALUES ("Winsteen", 85, 0.906); 138 | INSERT INTO student_grades (name, number_grade, fraction_completed) 139 | VALUES ("Wincifer", 66, 0.7054); 140 | INSERT INTO student_grades (name, number_grade, fraction_completed) 141 | VALUES ("Winster", 76, 0.5013); 142 | INSERT INTO student_grades (name, number_grade, fraction_completed) 143 | VALUES ("Winstonia", 82, 0.9045); 144 | 145 | select name, number_grade, round(100.00 * fraction_completed) as percent_completed from student_grades; 146 | 147 | /* how many students have earned which letter grade */ 148 | select count(number_grade), 149 | case 150 | when number_grade > 90 then 'A' 151 | when number_grade > 80 then 'B' 152 | when number_grade > 70 then 'C' 153 | else 'F' 154 | end as 'letter_grade' 155 | from student_grades 156 | group by letter_grade; 157 | 158 | /* Marvel characters database 159 | https://gist.github.com/pamelafox/585364b62390ea720858 160 | */ 161 | 162 | /* Marvel Heroes and Villains 163 | Based on the website http://marvel.wikia.com/Main_Page 164 | with popularity data from http://observationdeck.io9.com/something-i-found-marvel-character-popularity-poll-cb-1568108064 165 | and power grid data from http://marvel.wikia.com/Power_Grid#Power 166 | Collected by: https://www.khanacademy.org/profile/Mentrasto/ 167 | */ 168 | 169 | CREATE TABLE marvels (ID INTEGER PRIMARY KEY, 170 | name TEXT, 171 | popularity INTEGER, 172 | alignment TEXT, 173 | gender TEXT, 174 | height_m NUMERIC, 175 | weight_kg NUMERIC, 176 | hometown TEXT, 177 | intelligence INTEGER, 178 | strength INTEGER, 179 | speed INTEGER, 180 | durability INTEGER, 181 | energy_Projection INTEGER, 182 | fighting_Skills INTEGER); 183 | 184 | INSERT INTO marvels VALUES(1, "Spider Man", 1, "Good", "Male", 1.78, 75.75, "USA", 4, 4, 3, 3, 1, 4); 185 | INSERT INTO marvels VALUES(2, "Iron Man", 20, "Neutral", "Male", 1.98, 102.58, "USA", 6, 6, 5, 6, 6, 4); 186 | INSERT INTO marvels VALUES(3, "Hulk", 18, "Neutral", "Male", 2.44, 635.29, "USA", 6, 7, 3, 7, 5, 4); 187 | INSERT INTO marvels VALUES(4, "Wolverine", 3, "Good", "Male", 1.6, 88.46, "Canada", 2, 4, 2, 4, 1, 7); 188 | INSERT INTO marvels VALUES(5, "Thor", 5, "Good", "Male", 1.98, 290.3, "Norway", 2, 7, 7, 6, 6, 4); 189 | INSERT INTO marvels VALUES(6, "Green Goblin", 91, "Bad", "Male", 1.93, 174.63, "USA", 4, 4, 3, 4, 3, 3); 190 | INSERT INTO marvels VALUES(7, "Magneto", 11, "Neutral", "Male", 1.88, 86.18, "Germany", 6, 3, 5, 4, 6, 4); 191 | INSERT INTO marvels VALUES(8, "Thanos", 47, "Bad", "Male", 2.01, 446.79, "Titan", 6, 7, 7, 6, 6, 4); 192 | INSERT INTO marvels VALUES(9, "Loki", 32, "Bad", "Male", 1.93, 238.14, "Jotunheim", 5, 5, 7, 6, 6, 3); 193 | INSERT INTO marvels VALUES(10, "Doctor Doom", 19, "Bad", "Male", 2.01, 188.24, "Latveria", 6, 4, 5, 6, 6, 4); 194 | INSERT INTO marvels VALUES(11, "Jean Greay", 8, "Good", "Female", 1.68, 52.16, "USA", 3, 2, 7, 7, 7, 4); 195 | INSERT INTO marvels VALUES(12, "Rogue", 4, "Good", "Female", 1.73, 54.43, "USA", 7, 7, 7, 7, 7, 7); 196 | 197 | /* most popular and least popular */ 198 | select name, min(popularity) from marvels; 199 | select name, max(popularity) from marvels; 200 | 201 | 202 | 203 | 204 | 205 | 206 | -------------------------------------------------------------------------------- /practice/exercises.js: -------------------------------------------------------------------------------- 1 | console.log(getPowerset('abc')); 2 | 3 | // '' => [''] 4 | // 'a' => ['', 'a'] 5 | // 'ab' => ['', 'a', 'b', 'ab'] 6 | // 'abc' => ['', 'a', 'b', 'c', 'ab', 'ac', 'bc', 'abc'] 7 | 8 | // solution: https://rosettacode.org/wiki/Power_set#JavaScript 9 | 10 | function getPowerset(input){ 11 | // var counter = 0, output = [], inputArr = input.split(''); 12 | // var start = ''; 13 | 14 | // while(counter < inputArr.length){ 15 | // output.push(start); 16 | // for(var i = 0; i < inputArr.length; i++){ 17 | // start = inputArr[i]; 18 | // output.push(start); 19 | // } 20 | 21 | // counter++; 22 | // } 23 | // return output; 24 | } 25 | 26 | 27 | 28 | // Given an array a that contains only numbers in the range from 1 to a.length, find the first 29 | // duplicate number for which the second occurrence has the minimal index. In other words, if 30 | // there are more than 1 duplicated numbers, return the number for which the second occurrence 31 | // has a smaller index than the second occurrence of the other number does. If there are no such 32 | // elements, return -1. 33 | // Source: Codefights 34 | 35 | function firstDuplicate(arr) { 36 | 37 | // find duplicates 38 | var counts = arr.map((a, i)=>{ 39 | return { name: a, count: 1, index: i}; 40 | }); 41 | 42 | var totals = counts.reduce(function(a, b, i){ 43 | // handle >1 occurence 44 | if(typeof a[b.name] === 'object'){ 45 | return a; 46 | } 47 | 48 | if(a[b.name]){ 49 | a[b.name] = { count: a[b.name] + b.count, index: b.index }; 50 | } else { 51 | a[b.name] = b.count; 52 | } 53 | 54 | return a; 55 | }, {}); 56 | 57 | var hasDuplicates = false; 58 | var counts = []; 59 | 60 | for(var item in totals){ 61 | if(typeof totals[item] === 'object'){ 62 | hasDuplicates = true; 63 | counts.push(Object.assign({name: item }, totals[item])); 64 | } 65 | } 66 | 67 | // if no duplicates return -1 68 | if(!hasDuplicates) return -1; 69 | 70 | var minimal = arr.length; 71 | 72 | // get lowest index for duplicate 73 | counts.forEach((d)=>{ 74 | if(d.index < minimal) 75 | minimal = d.index; 76 | }); 77 | 78 | return arr[minimal]; 79 | } 80 | 81 | // Given a string s, find and return the first instance of a non-repeating character in it. 82 | // If there is no such character, return '_'. 83 | // Source: Codefights 84 | 85 | function firstNotRepeatingCharacter(str) { 86 | var repeats = []; 87 | for(var i = 0; i < str.length; i++){ 88 | repeats.push({ letter: str[i], count: 1 }); 89 | } 90 | 91 | var counts = repeats.reduce(function(a, b){ 92 | 93 | if(a[b.letter]) 94 | a[b.letter] += b.count; 95 | else 96 | a[b.letter] = 1; 97 | return a; 98 | }, {}); 99 | 100 | var nonrepeats = []; 101 | for (var k in counts){ 102 | if(counts[k] === 1) 103 | nonrepeats.push(k) 104 | } 105 | 106 | if (nonrepeats.length === 0) 107 | return '_'; 108 | 109 | var firstNonRepeater = str.length; 110 | nonrepeats.forEach(function(n){ 111 | if(str.indexOf(n) < firstNonRepeater) 112 | firstNonRepeater = n; 113 | }); 114 | return firstNonRepeater; 115 | } 116 | 117 | // You are given an n x n 2D matrix that represents an image. Rotate the image 118 | // by 90 degrees (clockwise). 119 | // Source: Codefights 120 | 121 | function rotateImage(img) { 122 | var output = []; 123 | var max = img[0].length; 124 | for(var i = 0; i < max; i++){ 125 | output.push([...Array(max)]); 126 | } 127 | 128 | for(var i = 0; i < max; i++){ 129 | var row = img[i]; 130 | 131 | for(var j = 0; j < max; j++){ 132 | output[j][i] = img[i][j] 133 | } 134 | } 135 | 136 | return output.map(function(row){ 137 | return row.reverse(); 138 | }); 139 | } 140 | 141 | // Return the number (count) of vowels in the given string. 142 | // Source: Codewars 143 | 144 | function getCount(str) { 145 | var vowelsCount = 0; 146 | str = str.toLowerCase(); 147 | var vowels = ['a', 'e', 'i', 'o', 'u']; 148 | 149 | for(let s of str){ 150 | 151 | if(vowels.includes(s)) vowelsCount += 1; 152 | } 153 | 154 | return vowelsCount; 155 | } 156 | 157 | // Return the next square if sq if a perfect square, -1 otherwise 158 | // Source: Codewars 159 | 160 | function findNextSquare(sq) { 161 | 162 | if (!Number.isInteger(Math.sqrt(sq))) return -1; 163 | 164 | var i = sq + 1; 165 | 166 | while(!Number.isInteger(Math.sqrt(i))){ 167 | i++; 168 | } 169 | 170 | return i; 171 | } 172 | 173 | // Finish the solution so that it returns the sum of all the multiples of 3 or 5 below the number passed in. 174 | // Source: Codewars 175 | 176 | function solution(number){ 177 | let sum = 0; 178 | number -= 1; 179 | while(number > 0){ 180 | if(number % 3 == 0 || number % 5 == 0){ 181 | sum += number; 182 | } 183 | number--; 184 | } 185 | 186 | return sum; 187 | } 188 | 189 | 190 | // You are going to be given an array of integers. Your job is to take that array and find an index N 191 | // where the sum of the integers to the left of N is equal to the sum of the integers to the right of N. 192 | // If there is no index that would make this happen, return -1. 193 | // Source: Codewars 194 | 195 | function sum(arr){ 196 | return arr.reduce(function(sum, value){ 197 | return sum + value; 198 | }, 0); 199 | } 200 | 201 | function findEvenIndex(arr) 202 | { 203 | for(var i=0; i < arr.length; i++){ 204 | let left = arr.slice(0, i); 205 | let right = arr.slice(i+1, arr.length); 206 | 207 | if (sum(left) == sum(right)) return i; 208 | } 209 | return -1; 210 | } 211 | 212 | 213 | // The new "Avengers" movie has just been released! There are a lot of people at the cinema 214 | // box office standing in a huge line. Each of them has a single 100, 50 or 25 dollars bill. 215 | // A "Avengers" ticket costs 25 dollars. Can Vasya sell a ticket to each person and give the 216 | // change if he initially has no money and sells the tickets strictly in the order people follow in the line? 217 | // Source: Codewars 218 | 219 | function tickets(peopleInLine){ 220 | let revenue = 0; 221 | let bills = {'25': 0, '50': 0, '100': 0}; 222 | 223 | for(var i = 0; i < peopleInLine.length; i++){ 224 | var person = peopleInLine[i], 225 | change = person - 25; 226 | 227 | bills[person] += 1; 228 | 229 | revenue = revenue + 25 - change; 230 | if(revenue < 0){ 231 | return 'NO'; 232 | } else { 233 | // give change 234 | if(change == 25){ 235 | if(bills[25] >= 1){ 236 | bills[25] -= 1; 237 | } else { 238 | return 'NO'; 239 | } 240 | } 241 | 242 | if (change == 50){ 243 | if (bills[50] != 0){ 244 | bills[50] -= 1; 245 | } else if (bills[25] >= 2) { 246 | bills[25] -= 2; 247 | } else { 248 | return 'NO'; 249 | } 250 | } 251 | 252 | if (change == 75){ 253 | if (bills[25] >= 1 && bills[50] >= 1) { 254 | bills[25] -= 1; 255 | bills[50] -= 1; 256 | } else if (bills[25] >= 3){ 257 | bills[25] -= 3; 258 | } else { 259 | return 'NO'; 260 | } 261 | } 262 | } 263 | }; 264 | return 'YES'; 265 | } 266 | 267 | 268 | // Implement the function unique_in_order which takes as argument a 269 | // sequence and returns a list of items without any elements with the same value 270 | // next to each other and preserving the original order of elements 271 | 272 | var uniqueInOrder=function(iterable){ 273 | let output = []; 274 | for(var i = 0; i < iterable.length; i++){ 275 | if(iterable[i] !== iterable[i-1]){ 276 | output.push(iterable[i]); 277 | } 278 | } 279 | return output; 280 | } 281 | 282 | 283 | //Given two arrays a and b write a function comp(a, b) that checks whether the two arrays have the 284 | // "same" elements, with the same multiplicities. "Same" means, here, that the elements in b are 285 | // the elements in a squared, regardless of the order. 286 | 287 | function comp(array1, array2){ 288 | try { 289 | array1.sort((a,b) => a-b); array2.sort((a,b) => a-b); 290 | } catch(e) { return false; } 291 | 292 | for(var i = 0; i < array1.length; i++){ 293 | if((array1[i] * array1[i]) !== array2[i]){ 294 | return false; 295 | } 296 | } 297 | return true; 298 | } 299 | 300 | 301 | // accum("abcd"); // "A-Bb-Ccc-Dddd" 302 | // accum("RqaEzty"); // "R-Qq-Aaa-Eeee-Zzzzz-Tttttt-Yyyyyyy" 303 | // accum("cwAt"); // "C-Ww-Aaa-Tttt" 304 | function accum(s) { 305 | let output = [], i = 0; 306 | 307 | for(letter of s){ 308 | output.push(letter.toUpperCase() + letter.toLowerCase().repeat(i)); 309 | i++; 310 | } 311 | return output.join('-'); 312 | } 313 | 314 | 315 | // In DNA strings, symbols "A" and "T" are complements of each other, as "C" and "G". 316 | // You have function with one side of the DNA; you need to get the other complementary side. 317 | // DNA strand is never empty or there is no DNA at all 318 | 319 | function DNAStrand(dna){ 320 | var DNA = Array.of(...dna); 321 | 322 | return DNA.map((curr, i)=>{ 323 | if(curr == 'A') return 'T'; 324 | 325 | if(curr == 'T') return 'A'; 326 | 327 | if(curr == 'C') return 'G'; 328 | 329 | if(curr == 'G') return 'C'; 330 | }).join(''); 331 | } 332 | 333 | // Write a method that takes an array of consecutive (increasing) letters as input and 334 | // that returns the missing letter in the array. 335 | 336 | function findMissingLetter(array){ 337 | for(var i = 0; i < array.length; i++){ 338 | var currentPlusOne = array[i].charCodeAt(0) + 1; 339 | var next = array[i+1].charCodeAt(0); 340 | 341 | if(currentPlusOne !== next){ 342 | return String.fromCharCode(currentPlusOne); 343 | } 344 | } 345 | } 346 | 347 | 348 | // Sort a sorted array by their squares 349 | // [1,2,3] => [1, 4, 9] 350 | // [-10, -1, 0, 1, 2] => [0, 1, 1, 4, 100] 351 | 352 | function sortNums(arr){ 353 | var start = 0, end = arr.length - 1, output = []; 354 | 355 | while (start <= end) { 356 | if (Math.abs(arr[start]) > Math.abs(arr[end])) 357 | { 358 | output.unshift(Math.pow(arr[start], 2)) 359 | start++; 360 | } else { 361 | output.unshift(Math.pow(arr[end], 2)) 362 | end--; 363 | } 364 | } 365 | 366 | return output; 367 | } 368 | 369 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Coding Interviews 2 | 3 | This is a list of concepts it is important to learn in order to coding interviews at big companies and for jobs with really technical teams. Not all companies interview this way but many do or at least include CS fundamental and puzzle questions as part of their processes. Preparing for these types of interviews can be challenging and tedious. I created this repo as a collection of resources to help better understand where these questions come from. There are tons of resources out there so if you are looking to crack the coding interview, well, definitely read cracking the coding interview (links below) and review some of the sites and concepts below. I also recommend [interviewing.io](https://interviewing.io/) for doing live practice interviews to get you prepared. 4 | 5 | If you have feedback for the repo or are looking for help on job search (interview prep, resume review etc) shoot me an email: connorleech@gmail.com or [tweet connor11528](https://twitter.com/connor11528) 6 | 7 | Thanks for stopping by 8 | 9 | - [**The 2 types of software engineering interviews and how to prepare for them**](https://codeburst.io/the-2-types-of-software-engineering-interviews-and-how-to-prepare-for-them-2e7bd4daa0b) 10 | 11 | ## Side Projects 12 | 13 | - [Indie Hackers](https://www.indiehackers.com/) 14 | 15 | - [How to build a startup — without quitting your day job](https://www.indiehackers.com/@aytekin/how-to-build-a-startup-without-quitting-your-day-job-d9d1176709) 16 | 17 | - [How to Talk About Your Side Projects](https://medium.freecodecamp.org/how-to-talk-about-your-side-projects-18b96f192817) 18 | 19 | ## Data Structures 20 | 21 | - Array 22 | 23 | - Hash Table 24 | 25 | - Linked List 26 | 27 | - Tree / Binary Tree 28 | 29 | - Graph 30 | 31 | - Stack 32 | 33 | - Queue 34 | 35 | - :octocat: **thejameskyle/itsy-bitsy-data-structures** - All the things you didn't know you wanted to know about data structures - https://github.com/thejameskyle/itsy-bitsy-data-structures 36 | 37 | ## Searching and Sorting 38 | 39 | - Binary Search 40 | 41 | - Breadth First Search (BFS) 42 | 43 | - Depth First Search (DFS) 44 | 45 | - Counting Sort 46 | 47 | - Quicksort 48 | 49 | - Merge Sort 50 | 51 | ## Concepts 52 | 53 | - Recursion: [JS interview prep: Recursion](https://tech.io/playgrounds/5422/js-interview-prep-recursion) (has runnable code examples) 54 | 55 | - Dynamic Programming: [Dynamic Programming - Rithm School](https://www.rithmschool.com/courses/javascript-computer-science-fundamentals/dynamic-programming), [video](https://www.youtube.com/watch?v=W2ote4jCuYw) 56 | 57 | - Greedy Algorithm 58 | 59 | - Sliding Window 60 | 61 | - Divide and Conquer 62 | 63 | - Big-O Analysis (time complexity, space complexity) 64 | 65 | ## Learning Guides 66 | 67 | - **HackerRank Interview Prep Kit** - https://www.hackerrank.com/interview/interview-preparation-kit - Curated list of exercises from the HackerRank team organized around key concepts you'll need to know. 68 | 69 | - **Rithm School Computer Science Fundamentals with JavaScript** - https://www.rithmschool.com/courses/javascript-computer-science-fundamentals - I've been following along with some of this as I don't have a comp sci degree. They explain the concepts and then point you to additional resources for learning the material (like youtub videos and specific codewars problems) Very helpful. 70 | 71 | - **Coderbyte** - https://coderbyte.com/challenges/?a=true - Lots of programming challenges, access 10 for free otherwise $30 per month 72 | 73 | - :octocat: **yangshun/tech-interview-handbook** - 4k+ ⭐ repo with helpful non-technical tips. Additionally has section covering Algorithm, Front End and System Design questions 74 | 75 | - :octocat: **mr-mig/every-programmer-should-know** - https://github.com/mr-mig/every-programmer-should-know - Don't let the title scare you. This repo covers at a high level things ranging from *Career Tips* to *Data Structures*, *Security*, *Architecture* and *Algorithms*. It's a lot but can be helpful to overview concepts and find new things to learn 76 | 77 | - :octocat: **jwasham/google-interview-university** - https://github.com/jwasham/google-interview-university#final-review - One man's somewhat crazy task to become a google software engineer. 48k+ stars. I believe he ended up working at Amazon. go figure 78 | 79 | - **30 second interview questions** - https://github.com/fejes713/30-seconds-of-interviews - A list and website of common interview questions you're bound to encounter during tricky JS interviews. 80 | 81 | ## Finding companies to apply to 82 | 83 | - **https://whoishiring.io/** - Most impressive job site aggregator I've ever seen in my life. Scrapes all the boards and has a map of where every company is located. 84 | 85 | - **https://huntr.co/** - Tool for keeping your applications and search organized on a Trello-style board. they also have a chrome extension for quickly adding jobs from various sources. 86 | 87 | - **https://breezy.hr** - I used this one as a recruiter. It is actually built for HR departments but has a chrome extension and can be helpful for adding people and specific individuals you're reaching out to. This way you remember to follow up and can find like-minded people. One catch is that you need a custom email address like @your-domain.com. Signing up with your gmail account won't work. 88 | 89 | - **https://betalist.com/jobs/collections** - companies and jobs grouped by category like *female led startup* or *decentralize all the things* for blockchain related jobs. 90 | 91 | - :octocat: **https://github.com/connor11528/sf-companies** - shameless plug here. I've got another repo going with companies located in downtown San Francisco. The data is available as a CSV file and includes company addresses. 92 | 93 | ## Services 94 | 95 | - **exercism** - https://exercism.io/ - Level up your programming skills with 2,629 exercises across 48 languages, and insightful discussion with our dedicated team of welcoming mentors. Exercism is 100% free forever. 96 | 97 | - **codewars** - https://www.codewars.com/ - Codewars has thousands of questions generated by the community. You'll never run out of practice problems. They're organized by difficulty, concept and programming language. 98 | 99 | - **codefights** - https://codefights.com/ - Really great user interface and user experience. I like the gamification and points system they have going on. 100 | 101 | - **Irfan Baqui: ace coding interviews** - https://www.irfanbaqui.com/coding-interview-prep/ - get one free problem to practice each week and get the solution next week 102 | 103 | - **interviewing.io** - https://interviewing.io/ - Anonymously practice coding interviews with engineers from prominent tech companies. 104 | 105 | - **Interview Cake** - https://www.interviewcake.com/ - Interview Cake is a thoroughly documented site on programming interviews and concepts. It can be expensive for the year membership but if you're serious about buckling down to learn the fundamentals can be worth it. They also offer a money-back gaurantee. 106 | 107 | - **Pramp** - https://www.pramp.com/ref/gt7 - Real practice with *actual* engineers. Book a time and practice interviewing with real human beings 108 | 109 | - **LeetCode** - https://leetcode.com/ - Pick from an expanding library of more than 190 questions, code and submit your solution to see if you have solved it correctly. 110 | 111 | - **Coderbyte** - https://coderbyte.com/challenges/?a=true - Lots of programming challenges, access 10 for free otherwise $30 per month 112 | 113 | - **HackerRank** - https://www.hackerrank.com/domains - Very popular platform for practicing coding questions. HackerRank is used by companies to evaluate candidates also 114 | 115 | - **InterviewBit** - https://www.interviewbit.com/ - Practice Coding Interview Questions. Give us time and we get you the job you deserve. 116 | 117 | - **Codility** - https://codility.com/programmers/ - Become a better programmer. Develop your coding skills with our lessons. Take part in our challenges. 118 | 119 | - **Codility Solutions** - https://www.martinkysel.com/codility-solutions/ - One engineer's solutions to the codility.com problem sets. 120 | 121 | - **Testdome** - https://www.testdome.com/Tests - Get certified and prove your knowledge 122 | to potential employers. Score well on one of our public tests, and you will get a free certificate of achievement. 123 | 124 | - **CodeEval** - https://www.codeeval.com/ - Find out how you rate against top coders. Unlock awesome startup jobs and hacker deals. 125 | 126 | - **Outco.io** - https://outco.io/ - 1 month interview prep bootcamp in San Francisco 127 | 128 | ## Javascript 129 | 130 | - :octocat: **amilajack/js-algorithms** - https://github.com/amilajack/js-algorithms - A collection of algorithms written in javascript 131 | 132 | - :octocat: **benoitvallon/computer-science-in-javascript** - https://github.com/benoitvallon/computer-science-in-javascript - Computer science reimplemented in JavaScript 133 | 134 | - :octocat: **lukehoban/es6features** - https://github.com/lukehoban/es6features - Overview of ECMAScript 6 features (21k+ stars) 135 | 136 | - **Khan Academy Algorithm Course** - https://www.khanacademy.org/computing/computer-science/algorithms 137 | 138 | - :octocat: **romyilano/Learning-JavaScript-Data-Structures-and-Algorithms** - https://github.com/romyilano/Learning-JavaScript-Data-Structures-and-Algorithms - Solutions to Learning JavaScript Data Structures and Algorithms by Loiane Groner ([book pdf](https://www.packtpub.com/application-development/learning-javascript-data-structures-and-algorithms)) 139 | 140 | - :octocat: **nzakas/computer-science-in-javascript** - https://github.com/nzakas/computer-science-in-javascript - Collection of classic computer science paradigms, algorithms, and approaches written in JavaScript. 141 | 142 | - :octocat: **JacopoDaeli/algorithmic-challenges** - https://github.com/JacopoDaeli/algorithmic-challenges - Solutions to algorithmic challenges written in C, Python, Java and JavaScript. 143 | 144 | - **Hack Reactor Prep** - http://www.hackreactor.com/prep-programs/ - free course and practice problems from Hack Reactor 145 | 146 | - **JS: Interview Algorithm** - http://www.thatjsdude.com/interview/js1.html - JS: Interview Algorithms questions and solutions 147 | 148 | ## PHP 149 | 150 | - **Efficient data structures for PHP 7** - https://medium.com/@rtheunissen/efficient-data-structures-for-php-7-9dda7af674cd - Medium article about implementing data structures with modern PHP 151 | 152 | - **30-seconds-of-php-code** - https://github.com/appzcoder/30-seconds-of-php-code - A curated collection of useful PHP snippets that you can understand in 30 seconds or less. 153 | 154 | - **SOLID Principles in PHP** - https://laracasts.com/series/solid-principles-in-php - SOLID represents a series of guidelines that developers can use to, if done well, simplify and clarify their code. 155 | 156 | - **Object Oriented Bootcamp in PHP** - https://laracasts.com/series/object-oriented-bootcamp-in-php - covers fundamentals of OOP in PHP, including tricky concepts like difference between Interfaces and Abstract Classes 157 | 158 | ## SQL 159 | 160 | - **Khan Academy SQL course** - https://www.khanacademy.org/computing/computer-programming/sql - Great course covering SQL principles. Highly recommend. 161 | 162 | ## Laravel 163 | 164 | - **Diving Laravel** - https://divinglaravel.com/ - A deep dive into laravel core, packages, and technologies by [@themsaid](https://github.com/themsaid) 165 | 166 | - **Advanced Eloquent** - https://laracasts.com/series/advanced-eloquent - Sure, you've learned the essentials of using Eloquent in your applications, but do you really understand what's going on under the hood? 167 | 168 | - :octocat: **unicodeveloper/laravel-exam** - https://github.com/unicodeveloper/laravel-exam - A Laravel exam with questions from beginner to expert curated by [@unicodeveloper](https://github.com/unicodeveloper) 169 | 170 | ## Git 171 | 172 | - **Git flow** - https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow - a git workflow that some companies follow to manage their deployments. 173 | 174 | - **Git Game** - https://www.git-game.com/ - The git-game is a terminal based game that teaches both new and advances users some pretty cool features of the git scm (source control management) system. 175 | 176 | ## Webpack 177 | 178 | - **webpack: The Core Concepts** - https://webpack.academy/p/the-core-concepts - less than an hour long course on webpack fundamentals from core team member 179 | 180 | ## Python 181 | 182 | - Algosaurus: http://algosaur.us/data-structures-basics/ 183 | 184 | ## Ruby 185 | 186 | - :octocat: **Haseeb-Qureshi/Algorithms-Study-Group** - https://github.com/Haseeb-Qureshi/Algorithms-Study-Group 187 | 188 | ## Books 189 | 190 | - **Learning JavaScript Data Structures and Algorithms** - https://github.com/loiane/javascript-datastructures-algorithms 191 | 192 | - **Cracking the Coding Interview** ([pdf](https://inspirit.net.in/books/placements/Cracking%20the%20Coding%20Interview.pdf), [pdf alt](https://github.com/navyifanr/Cracking_the_coding_interview/blob/master/Cracking%20the%20coding%20interview-ctci.pdf)) 193 | 194 | - :octocat: **amilajack/reading** - list of computer science readings with book pdfs - https://github.com/amilajack/reading - Reading List: 195 | 196 | ## Algorithm visualization 197 | 198 | - Visualgo: https://visualgo.net/en 199 | 200 | ## Articles 201 | 202 | - I just got a developer job at Facebook. Here’s how I prepped for my interviews: https://medium.freecodecamp.org/software-engineering-interviews-744380f4f2af 203 | 204 | - How to write a great résumé for software engineers: https://medium.freecodecamp.org/how-to-write-a-great-resume-for-software-engineers-75d514dd8322 205 | 206 | - Why You Don’t Deserve That Dream Developer Job: https://codeburst.io/why-you-dont-deserve-that-dream-developer-job-60d5e5adb8d7 207 | 208 | - Top 8 Mistakes to avoid in Technical Interviews According to Data: https://blog.pramp.com/top-8-mistakes-in-technical-interviews-according-to-data-27d2572bda1f 209 | 210 | - Resource List: Getting hired at technology startups: https://notes.breakoutlist.com/resource-list-getting-hired-at-technology-startups-9f981518a0d9 211 | 212 | - Resource List: Figuring out what you want / your “purpose”: https://notes.breakoutlist.com/resource-list-figuring-out-what-you-want-your-purpose-b7af89e2ba7 213 | 214 | - Triplebyte blog, How to pass a programming interview: http://blog.triplebyte.com/how-to-pass-a-programming-interview 215 | 216 | - Jeff Atwood, How to Hire a Programmer: https://blog.codinghorror.com/how-to-hire-a-programmer/ 217 | 218 | - Joel On Software, The Guerrilla Guide to Interviewing (version 3.0): https://www.joelonsoftware.com/2006/10/25/the-guerrilla-guide-to-interviewing-version-30/ 219 | 220 | - Coding Interview Tips, How to get better at technical interviews without practicing: https://www.interviewcake.com/coding-interview-tips 221 | 222 | - software engineer resume template: https://notes.breakoutlist.com/best-engineer-resume-template-uses-latex-14380b4a239f 223 | 224 | - Guide to interviewing your future manager before deciding where to work: https://notes.breakoutlist.com/guide-to-interviewing-your-future-manager-before-deciding-where-to-work-3b2eb3326793 225 | 226 | ## More Questions 227 | 228 | - **500 Data Structures and Algorithms practice problems and their solutions** - https://techiedelight.quora.com/500-Data-Structures-and-Algorithms-practice-problems-and-their-solutions - these are good because they are grouped by topic such as array, BST, Dynamic Programming etc 229 | 230 | - **Project Euler** - https://projecteuler.net/archives - The classic 231 | 232 | - **Epic List of Interview Questions** - http://katemats.com/interview-questions/ - a list of software engineer skills or areas that can be tested and evaluated in an interview context 233 | 234 | - :octocat: **MaximAbramchuck/awesome-interview-questions** - https://github.com/MaximAbramchuck/awesome-interview-questions - A curated awesome list of lists of interview questions. 235 | 236 | ## Technical blogs 💸 237 | 238 | This is tangentially related to interviews. Below is a list of companies that feature blog posts from guest authors. Blogging and teaching others can be a powerful way to comprehend new material, fine tune your writing skills, gain exposure and potentially even make money! If you have a technical blog open to new contributors please [submit a PR](https://github.com/connor11528/coding-interviews/pulls) 239 | 240 | - [Scotch.io](https://scotch.io/write-for-us) - this has been my go to source for web development tutorials for years. Code on the rocks 241 | 242 | - [Snipcart](https://snipcart.com/guest-posting) - company interested in Vue.js, eCommerce, Javascript and the JAMstack. There is some really great writing and code samples on here 243 | 244 | - [JScrambler](https://blog.jscrambler.com/) - company interested in Javascript tutorials. I wrote a post for them on using Vue.js and Vuelog to make a static blogging app. Check out the full article [here](https://blog.jscrambler.com/generate-a-static-markdown-blog-using-vuelog/) 245 | 246 | ## Words of wisdom 247 | 248 | [Charlie Munger](https://www.cnbc.com/2017/08/16/warren-buffetts-partner-charlie-munger-has-3-rules-for-a-career.html), Warren Buffett’s partner, has three rules for a career: 249 | 250 | 1) Don’t sell anything you wouldn’t buy yourself 251 | 2) Don’t work for anyone you don’t respect and admire 252 | 3) Work only with people you enjoy 253 | 254 | --------------------------------------------------------------------------------