【LeetCode】Add Binary

class Solution {public:    string addBinary(string a, string b) {        int aindex = a.size() - 1;int bindex = b.size() - 1;string c;int flag = 0,num;while (aindex>=0 && bindex>=0){num = a[aindex] - '0' + b[bindex] - '0'+flag;flag = num / 2;num %= 2;c = (char(num + '0')) + c;aindex--;bindex--;}while (aindex>=0){num = a[aindex] - '0' + flag;flag = num / 2;num %= 2;c = (char(num + '0')) + c;aindex--;}while (bindex >= 0){num = b[bindex] - '0' + flag;flag = num / 2;num %= 2;c = (char(num + '0')) + c;bindex--;}if (flag > 0){c = (char)(flag + '0') + c;}return c;    }};