leetcode刷题二十一

题目叙述

给你两个二进制字符串，返回它们的和（用二进制表示）。

输入为 非空 字符串且只包含数字 1 和 0。

题目解答

class Solution:
    def addBinary(self, a: str, b: str) -> str:
        l1 = len(a)
        l2 = len(b)
        l = 0
        c = []
        out = ''
        r = '0'

        if l1 == l2:
            l = l1
            pass  
        elif l1 > l2:
            l = l1
            for i in range(l1 - l2):
                b = b[::-1]
                b = b + '0' 
                b = b[::-1]
        else:
            l = l2
            for j in range(l2 - l1):
                a = a[::-1]
                a = a + '0'
                a = a[::-1]

        for k in range(l):
            if int(a[l - k - 1]) ^ int(b[l - k - 1]) ^ int(r) == 1:
                out += '1'
            else:
                out += '0'

            if int(r) * (int(a[l - k - 1]) ^ int(b[l - k - 1])) + int(a[l - k - 1]) * int(b[l - k - 1]) == 1:
                r = '1'
            else:
                r = '0'

        if r == '0':
            return  out[::-1]
        else:
            out = out + r
            return out[::-1]