Add Binary【二进制相加】

PROBLEM:

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

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

SOLVE（C++）:

class Solution{
public:
    string addBinary(string a, string b){
        string s = "";
        int c = 0, i = a.size() - 1, j = b.size() - 1;
        while(i >= 0 || j >= 0 || c == 1){
            c += i >= 0 ? a[i --] - '0' : 0;
            c += j >= 0 ? b[j --] - '0' : 0;
            s = char(c % 2 + '0') + s;
            c /= 2;
        }
        return s;
    }
};

该解法写的很简练。