415._add_strings.md

415. Add Strings

难度: Easy

刷题内容

原题连接

• https://leetcode.com/problems/add-strings

内容描述

Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2.

Note:

The length of both num1 and num2 is < 5100.
Both num1 and num2 contains only digits 0-9.
Both num1 and num2 does not contain any leading zero.
You must not use any built-in BigInteger library or convert the inputs to integer directly.

解题方案

思路 1

题目说不能直接将input转换为int，那我就一次只转换一位，真tm简单！

class Solution(object):
    def addStrings(self, num1, num2):
        """
        :type num1: str
        :type num2: str
        :rtype: str
        """
        def str2int(num):
            res = 0
            for i in range(len(num)-1, -1, -1):
                res += int(num[i]) * pow(10, len(num)-1-i)
            return res
        return str(str2int(num1) + str2int(num2))