MULTIPLY STRINGS

https://leetcode.com/problems/multiply-strings/
class Solution:
    def multiply(self, num1: str, num2: str) -> str:
        num1,num2=num1[::-1],num2[::-1]
        m,n=len(num1),len(num2)
        res=[0]*(m+n)
        for i in range(m):
            for j in range(n):
                digit=int(num1[i])*int(num2[j])
                res[i+j]+=digit
                rem=res[i+j]//10
                res[i+j]=res[i+j]%10
                res[i+j+1]+=rem
        res=res[::-1]
        print(res)
        beg=-1
        for i in range(m+n):
            if res[i]!=0:
                beg=i
                break
        if beg==-1:
            return '0'
        res=res[beg:]

        res=map(str,res)
        return "".join(list(res))