数据结构算法操作试题(C++/Python)——字符串相乘

class Solution(object):
    def multiply(self, num1, num2):
        """
        :type num1: str
        :type num2: str
        :rtype: str
        """
        res = 0
        for i in range(1,len(num1)+1):
            for j in range(1, len(num2)+1):
                res += int(num1[-i]) * int(num2[-j]) *10**(i+j-2)
        return str(res)

class Solution(object):
    def multiply(self, num1, num2):
        """
        :type num1: str
        :type num2: str
        :rtype: str
        """
    return str(int(num1) * int(num2))