题目：

题解：

class Solution {
public:string addBinary(string a, string b) {string ans;reverse(a.begin(), a.end());reverse(b.begin(), b.end());int n = max(a.size(), b.size()), carry = 0;for (size_t i = 0; i < n; ++i) {carry += i < a.size() ? (a.at(i) == '1') : 0;carry += i < b.size() ? (b.at(i) == '1') : 0;ans.push_back((carry % 2) ? '1' : '0');carry /= 2;}if (carry) {ans.push_back('1');}reverse(ans.begin(), ans.end());return ans;}
};