Leetcode: Multiply Strings

Question

Given two numbers represented as strings, return multiplication of the numbers as a string.

Note: The numbers can be arbitrarily large and are non-negative.

Hide Tags Math String
Hide Similar Problems (M) Add Two Numbers (E) Plus One (E) Add Binary

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Solution

Get idea from here1, here2

class Solution(object):    def multiply(self, num1, num2):        """        :type num1: str        :type num2: str        :rtype: str        """        if len(num1)==0 or len(num2)==0 or num1=='0' or num2=='0':            return '0'        num1, num2 = list(num1), list(num2)        num1.reverse()        num2.reverse()        res = [0]*(len(num1)+len(num2))        for ind1 in range(len(num1)):            a = ord(num1[ind1]) - ord('0')            for ind2 in range(len(num2)):                b = ord(num2[ind2]) - ord('0')                res[ind1+ind2] += a*b        ress = []        carry = 0        for ind in range(len(res)):            digit = res[ind]%10            ress = [(digit+carry)%10] + ress            carry = res[ind]/10 + (digit+carry)/10        if len(ress)>0 and ress[0]==0:            ress = ress[1:]        ress = [str(elem) for elem in ress]        ress = ''.join(ress)        return ress