LeetCode题意分析&解答43. Multiply Strings

Posted 2020-06-27

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.

题意分析：

　　本题是求两个用string表示的非负大数的乘积，乘数可以是任意大小。

解答：

　　可以用一个临时List表示乘积的每一位，然后对两个乘数每一位两两相乘，并将结果填到相应的List坐标中即可。

AC代码：

class Solution(object):
    def multiply(self, num1, num2):
        ret_list = [0] * (len(num1) + len(num2))
        for i, vi in enumerate(reversed(num1)):
            for j, vj in enumerate(reversed(num2)):
                ret_list[i + j] += int(vi) * int(vj)
                ret_list[i + j + 1] += ret_list[i + j] / 10
                ret_list[i + j] %= 10
        while len(ret_list) > 1 and ret_list[-1] == 0:
            ret_list.pop()
        return ‘‘.join(map(str, ret_list[::-1]))