├── README.md
├── Week 2
    ├── week2i.py
    └── week2ii.py
├── Week 3
    ├── week3i.py
    └── week3ii.py
├── Week 4
    ├── week4i.py
    └── week4ii.py
├── Week 5
    ├── week5i.py
    └── week5ii.py
└── Week 8
    └── week8.py


/README.md:
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1 | # Programming, Data Structures and Algorithms using Python - NPTEL
2 | 
3 | This repository contains the solutions of the course Programming, Data Structures and Algorithms using Python[2019 Jan-Mar] course in NPTEL
4 | Here's the link for the course: https://onlinecourses.nptel.ac.in/noc19_cs08
5 | 


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/Week 2/week2i.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=98
 3 | 
 4 | def intreverse(n):
 5 |     #alternative version
 6 |     #r=0;
 7 |     #while(n!=0):
 8 |     #   (r,n)=(r*10+n%10,n//10);
 9 |     return int(str(n)[-1::-1]);
10 | 
11 | def matched(s):
12 |     stack=[];
13 |     for i in s:
14 |         if(i=='('):
15 |             stack.append('(');
16 |         elif(i==')'):
17 |             try:
18 |                 stack.pop();
19 |             except IndexError:
20 |                 return False;
21 |     if(stack==[]):
22 |         return True;
23 |     return False;
24 | 
25 | def sumprimes(l):
26 |     sum=0;
27 |     for i in l:
28 |         if(isprime(i)):
29 |             sum=sum+i;
30 |     return sum;
31 | 
32 | def isprime(n):
33 |     if(n<=1):
34 |         return False;
35 |     for i in range(2,int(n**0.5)+1):
36 |         if(n%i==0):
37 |             return False;
38 |     return True;
39 | 


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/Week 2/week2ii.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=99
 3 | 
 4 | def isprime(n):
 5 |     if(n<=1):
 6 |         return False;
 7 |     for i in range(2,int(n**0.5)+1):
 8 |         if(n%i==0):
 9 |             return False;
10 |     return True;
11 | 
12 | def prime_generator(n):
13 |     for i in range(2,n):
14 |         if(isprime(i)):
15 |             yield i;
16 | 
17 | def primepartition(n):
18 |     #alternative version
19 |     #if(n<=3):
20 |     #    return False;
21 |     #for i in range(1,n):
22 |     #    if(isprime(i) and isprime(n-i)):
23 |     #        return True;
24 |     #return False;
25 |     prime=prime_generator(n);
26 |     while(True):
27 |         try:
28 |             i=next(prime);
29 |         except Exception:
30 |             return False;
31 |         if(isprime(n-i)):
32 |             return True;
33 |     return False;
34 | 
35 | def nestingdepth(s):
36 |     stack=[];
37 |     maxi=0;
38 |     depth=0;
39 |     for i in s:
40 |         if(i=='('):
41 |             stack.append('(');
42 |             depth+=1;
43 |         elif(i==')'):
44 |             try:
45 |                 stack.pop();
46 |                 depth-=1;
47 |             except IndexError:
48 |                 return -1;
49 |         if(maxi<depth):
50 |             maxi=depth;
51 |     if(stack==[]):
52 |         return maxi;
53 |     return -1;
54 | 
55 | 
56 | def rotatelist(l,k):
57 |     k=k%(len(l));
58 |     return l[k:]+l[:k];
59 | 
60 | 


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/Week 3/week3i.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=101
 3 | 
 4 | def descending(l):
 5 |     i,j=0,1;
 6 |     n=len(l);
 7 |     while(j<n):
 8 |         if(l[i]<l[j]):
 9 |             return False;
10 |         i,j=i+1,j+1;
11 |     return True;
12 | 
13 | def valley(l):
14 |     inc,dec=1,1
15 |     i,j=0,1;
16 |     n=len(l);
17 |     flow='inc'
18 |     while(j<n):
19 |         if(l[i]>l[j] and flow=='inc'):
20 |             inc=inc+1;
21 |         elif(l[i]<l[j] and flow=='inc'):
22 |             flow='dec';
23 |             dec=dec+1;
24 |         elif(l[i]<l[j] and flow=='dec'):
25 |             dec=dec+1;
26 |         else:
27 |             return False;
28 |         i,j=i+1,j+1;
29 |     if(inc>=2 and dec>=2):
30 |         return True;
31 |     return False;
32 | 
33 | def transpose(m):
34 |     #alternative version
35 |     #import numpy as np
36 |     #ar=np.array(m);
37 |     #return [list(i) for i in ar.transpose()];
38 |     s=[];
39 |     n=len(m[0]);
40 |     for i in range(n):
41 |         s.append([j[i] for j in m]);
42 |         #k=[];
43 |         #for j in m:
44 |         #    k.append(j[0]);
45 |         #s.append(k);
46 |     return s;
47 | 


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/Week 3/week3ii.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=102
 3 | 
 4 | def progression(l):
 5 |   i,j=0,1;
 6 |   n=len(l);
 7 |   if(n<=1):
 8 |     return True; 
 9 |   d=l[0]-l[1];
10 |   while(j<n):
11 |     if(l[i]-l[j]!=d):
12 |       return False; 
13 |     i,j=i+1,j+1;
14 |   return True;
15 | 
16 | def primesquare(l):
17 |     n=len(l);
18 |     if(n<=1):
19 |         return True;
20 |     return square_prime(l,0) or square_prime(l,1);
21 | 
22 | #wrong submission :(
23 | '''def square_prime(l,rem):
24 |     start=l[rem];
25 |     n=len(l);
26 |     for i in range(n):
27 |         if(i%2==rem):
28 |             if(l[i]!=start**(i//2+1)):
29 |                 return False;
30 |         else:
31 |             if(not isprime(l[i])):
32 |                 return False;
33 |     return True;
34 | '''
35 | 
36 | def square_prime(l,rem):
37 |   n=len(l);
38 |   for i in range(n):
39 |     if(i%2==rem):
40 |       if(not issquare(l[i])):
41 |         return False;
42 |     else:
43 |       if(not isprime(l[i])):
44 |         return False;
45 |   return True;
46 | 
47 | def issquare(n):
48 |   return int(n**0.5)**2==n;
49 | 
50 | def isprime(n):
51 |     if(n<=1):
52 |         return False;
53 |     for i in range(2,int(n**0.5)+1):
54 |         if(n%i==0):
55 |             return False;
56 |     return True;
57 | 
58 | def matrixflip(m,d):
59 |     m=m[:]
60 |     if(d=='h'):
61 |         n=len(m);
62 |         for i in range(n):
63 |             m[i]=m[i][-1::-1];
64 |     elif(d=='v'):
65 |         m=m[-1::-1];
66 |     return m;
67 | 


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/Week 4/week4i.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=105
 3 | 
 4 | def orangecap(d):
 5 |   total={};
 6 |   for match in d.keys():
 7 |     for player in d[match].keys():
 8 |       try:
 9 |         total[player]+=d[match][player];
10 |       except:
11 |         total[player]=d[match][player];
12 |   maxi=(-1,-1);
13 |   for player,score in total.items():
14 |     if(score>maxi[1]):
15 |       maxi=(player,score);
16 |   return maxi;
17 | 
18 | def addpoly(p1,p2):
19 |     result=[];
20 |     i1,i2=0,0;
21 |     l1,l2=len(p1),len(p2);
22 |     while(i1<l1 and i2<l2):
23 |         if(p1[i1][1]>p2[i2][1]):
24 |             result.append(p1[i1]);
25 |             i1+=1;
26 |         elif(p1[i1][1]<p2[i2][1]):
27 |             result.append(p2[i2]);
28 |             i2+=1;
29 |         else:
30 |             if(p1[i1][0]+p2[i2][0]!=0):
31 |                 result.append((p1[i1][0]+p2[i2][0],p1[i1][1]));
32 |             i1+=1;
33 |             i2+=1;
34 |     while(i1<l1):
35 |         result.append(p1[i1]);
36 |         i1+=1;
37 |     while(i2<l2):
38 |         result.append(p2[i2]);
39 |         i2+=1;
40 |     return result;
41 | 
42 | def multpoly(p1,p2):
43 |     result_dict=dict();
44 |     for coeff1,exp1 in p1:
45 |         for coeff2,exp2 in p2:
46 |             try:
47 |                 result_dict[exp1+exp2] += coeff1*coeff2;
48 |             except:
49 |                 result_dict[exp1+exp2] = coeff1*coeff2;
50 |     return sorted([(coeff,exp) for exp,coeff in result_dict.items() if coeff!=0],key=lambda x: x[1],reverse=True);
51 | 


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/Week 4/week4ii.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=106
 3 | 
 4 | import sys
 5 | sys.setrecursionlimit=10000;
 6 | def rainaverage(city_rain):
 7 |     city_rain_list=dict();
 8 |     for city,rain in city_rain:
 9 |         try:
10 |             city_rain_list[city].append(rain);
11 |         except:
12 |             city_rain_list[city]=[rain];
13 |     city_rain_avg=dict();
14 |     for city,rain in city_rain_list.items():
15 |         city_rain_avg[city]=sum(rain)/len(rain);
16 |     return sorted(city_rain_avg.items(),key=lambda x:x[0]);
17 | 
18 | def flatten(complex_list):
19 |     simple_list=[];
20 |     for i in complex_list:
21 |         if(type(i)!=list):
22 |             simple_list.append(i);
23 |         else:
24 |             simple_list = simple_list + flatten(i);
25 |     return simple_list
26 | 


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/Week 5/week5i.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?action=submit&name=108
 3 | 
 4 | import sys
 5 | 
 6 | def sort_key(student):
 7 |     return student[0];
 8 | 
 9 | current = 'Courses';
10 | courses = dict();
11 | students = dict();
12 | grades = dict();
13 | grade_points = {'A':10,'AB':9,'B':8,'BC':7,'C':6,'CD':5,'D':4}
14 | while(True):
15 |     line = input();
16 |     if(line == 'Courses'):
17 |         current = 'Courses';
18 |         continue;
19 |     elif(line == 'Students'):
20 |         current = 'Students'
21 |         continue;
22 |     elif(line == 'Grades'):
23 |         current = 'Grades';
24 |         continue;
25 |     elif(line == 'EndOfInput'):
26 |         break;
27 |     elif(current == 'Courses'):
28 |         code,name,sem,year,instr = line.split('~');
29 |         courses[code] = (name,sem,year,instr);
30 |     elif(current == 'Students'):
31 |         roll,name = line.split('~');
32 |         students[roll] = name;
33 |     elif(current == 'Grades'):
34 |         code,sem,year,roll,grade = line.split('~');
35 |         try:
36 |             grades[roll].append((code,sem,year,grade_points[grade]));
37 |         except:
38 |             grades[roll] = [(code,sem,year,grade_points[grade])];
39 | 
40 | students = sorted(students.items(), key=sort_key);
41 | for student in students:
42 |     line = student[0]+'~'+student[1]+'~';
43 |     points = 0;
44 |     try:
45 |         for grade in grades[student[0]]:
46 |             points += grade[3];
47 |         points = round(points/len(grades[student[0]]),2)
48 |     except:
49 |         pass;
50 |     line += str(points);
51 |     print(line);
52 | 


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/Week 5/week5ii.py:
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 1 | #link for question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?action=submit&name=109
 3 | 
 4 | import sys
 5 | 
 6 | def sort_key(checkout):
 7 |     key = list(map(int,checkout[1].split('-')));
 8 |     key.append(borrowers[checkout[0][0]]);
 9 |     key.append(checkout[0][1]);
10 |     return tuple(key);
11 | 
12 | current = 'Books';
13 | books = dict();
14 | borrowers = dict();
15 | checkouts = dict();
16 | while(True):
17 |     line = input();
18 |     if(line == 'Books'):
19 |         current = 'Books';
20 |         continue;
21 |     elif(line == 'Borrowers'):
22 |         current = 'Borrowers'
23 |         continue;
24 |     elif(line == 'Checkouts'):
25 |         current = 'Checkouts';
26 |         continue;
27 |     elif(line == 'EndOfInput'):
28 |         break;
29 |     elif(current == 'Books'):
30 |         acc_no,title = line.split('~');
31 |         books[acc_no] = title;
32 |     elif(current == 'Borrowers'):
33 |         usr,name = line.split('~');
34 |         borrowers[usr] = name;
35 |     elif(current == 'Checkouts'):
36 |         usr,acc_no,due_date = line.split('~');
37 |         checkouts[(usr,acc_no)] = due_date;
38 | 
39 | checkouts = sorted(checkouts.items(), key=sort_key);
40 | 
41 | for checkout in checkouts:
42 |     line = checkout[1]+'~'+borrowers[checkout[0][0]]+'~'+\
43 |            checkout[0][1]+'~'+books[checkout[0][1]]
44 |     print(line);
45 | 


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/Week 8/week8.py:
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 1 | #link for the question
 2 | #https://onlinecourses.nptel.ac.in/noc19_cs08/progassignment?name=116
 3 | 
 4 | def longestPalSubstr(string):
 5 |     maxLength = 1
 6 |     start = 0
 7 |     length = len(string)
 8 |     low = 0
 9 |     high = 0
10 |     for i in range(1, length):
11 |         low = i - 1
12 |         high = i
13 |         while low >= 0 and high < length and string[low] == string[high]:
14 |             if high - low + 1 > maxLength:
15 |                 start = low
16 |                 maxLength = high - low + 1
17 |             low -= 1
18 |             high += 1
19 |         low = i - 1
20 |         high = i + 1
21 |         while low >= 0 and high < length and string[low] == string[high]:
22 |             if high - low + 1 > maxLength:
23 |                 start = low
24 |                 maxLength = high - low + 1
25 |             low -= 1
26 |             high += 1
27 |     return maxLength,string[start:start + maxLength]
28 | n=int(input());
29 | s=input();
30 | l=longestPalSubstr(s)
31 | print(l[0],l[1],sep='\n');
32 | 


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