[leetcode] 67. Add Binary 解题报告

题目链接：https://leetcode.com/problems/add-binary/

Given two binary strings, return their sum (also a binary string).

For example,
a = "11"
b = "1"
Return "100".

思路：字符串相加, 没什么好说的, 但是还是要尽量写的干净

class Solution {public:    string addBinary(string a, string b) {        int len1 = a.size(), len2 = b.size(), flag = 0;        string ans;        while(len1 > 0 || len2 > 0)        {            int val = 0;            if(len1 > 0) val += a[--len1] - '0';            if(len2 > 0) val += b[--len2] - '0';            ans.insert(ans.begin(), '0'+(val+flag)%2);            flag = (val+flag)/2;        }        if(flag) ans = "1" + ans;        return ans;    }};