Answer to Question #189797 in Python for phani

Question

Add two polynomials
Given two polynomials A and B, write a program that adds the given two polynomials A and B.
Input

The first line contains a single integer M. 
Next M lines contain two integers Pi, Ci separated with space, where Pi denotes power and Ci denotes co-efficient of Pi for polynomial A.
After that next line contains a single integer N.
Next N lines contain two integers Pj, Cj separated with space, where Pj denotes power and Cj denotes co-efficient of Pj for polynomial B.
  
Explanation

If M = 4 and for polynomial A
For power 0, co-efficient is 5
For power 1, co-efficient is 0
For power 2, co-efficient is 10
For power 3, co-efficient is 6.

If N = 3 and for polynomial B
For power 0, co-efficient is 1
For power 1, co-efficient is 2
For power 2, co-efficient is 4.
Then polynomial A represents "6x^3 + 10x^2 + 5", the polynomial B represents "4x^2 + 2x + 1" and the addition of A and B is "6x^3 + 14x^2 + 2x + 6"
Sample Input 
4
0 5
1 0
2 10
3 6
3
0 1
1 2
2 4
Sample Output 
6x^3 + 14x^2 + 2x + 6

Answer 1

def enter_polinom():


    while  True:
        try:
            N = int(input(''))
        except:
            print('enter positive integer')
            continue
        if N < 0:
            print('enter positive integer')
            continue
        break
    P = []
    k = 0
    while k < N:
        try:
            t = list(map(int, input('').split()))
            if len(t) != 2:
                print('enter two integers')
                continue
            k += 1
        except:
            print('enter two integers')
            continue
        add = True
        for i in range(len(P)):
            if P[i][0] == t[0]:
                P[i][1] += t[1]
                add = False
        if add:
            P.append(t) 
    return P


def add_polinoms(pol_1, pol_2):
        added = []
        while pol_1 or pol_2:
                if pol_1:
                        tmp = pol_1.pop(0)
                        for i in range(len(pol_2)):
                                if pol_2[i][0] == tmp[0]:
                                        tmp[1] += pol_2[i][1]
                                        pol_2.pop(i)
                                        break
                else:
                        tmp = pol_2.pop(0)


                added.append(tmp)
        added.sort(reverse=True)
        return(added)


def print_polinom(p):


    s = ''
    first = True
    if len(p) == 0:
        print(0)
        return
    elif p[0][1] < 0:
        if p[0][0] == 0:
            s += '{}'.format(p[0][1])
        else:
            if p[0][1] == -1:
                if p[0][0] == 1:
                    s += '-x'
                else:
                    s += '-x^{}'.format(p[0][0])
            else:
                if p[0][0] == 1:
                    s += '{}x'.format(p[0][1])
                else:
                    s += '{}x^{}'.format(p[0][1],p[0][0])
        p.pop(0)
        first = False    
    for el in p:
        if el[1] == 0:
            continue
        elif el[1] < 0:
            s += ' - '
            el[1] = -el[1]
        else:
            if not first:
                s += ' + '
        if el[0] == 0:
            s += '{}'.format(el[1])
        elif el[0] == 1:
            s += '{}x'.format(el[1])
        else:
            s += '{}x^{}'.format(el[1], el[0])
        first = False
    print(s)


A = enter_polinom()
B = enter_polinom()
print_polinom(add_polinoms(A, B))