Add Binary

Add BinaryApr 2 '12

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

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

class Solution {  public:      string addBinary(string a, string b) {          // Start typing your C/C++ solution below          // DO NOT write int main() function          string ret;        int sum = 0;        for(int i = a.length()-1,j = b.length()-1; i >=0 || j>=0 ;i--,j--)        {            sum += i < 0 ? 0 : (a[i] - '0');            sum += j < 0 ? 0 : (b[j] - '0');            ret  = ((sum&1) ? "1" : "0") + ret;            sum = sum>>1;        }        return (sum&1) ? ("1"+ret):ret;    }  };  

20 milli secs