leetcode 67. Add Binary （高精度加法）

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

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

简单的二进制高精度加法。

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