Add Binary

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

For example,
a = "11"
b = "1"

Return "100".

对应leetcode上67题：https://leetcode.com/problems/add-binary/

题解：此题不难，但是要写得精炼，还是要学习下的。

class Solution {public:   string addBinary(string a, string b) {      string result;      const size_t n = a.size()>b.size()?a.size():b.size();      reverse(a.begin(),a.end());      reverse(b.begin(),b.end());      int carry = 0;      for(size_t i = 0;i<n;i++){          const int ai = i<a.size()?a[i]-'0':0;          const int bi = i<b.size()?b[i]-'0':0;          const int val = (ai+bi+carry)%2;          carry = (ai+bi+carry)/2;          result.insert(result.begin(),val+'0');      }      if(carry == 1){          result.insert(result.begin(),'1');      }      return result;   }};