[LintCode] Add Binary 二进制数相加

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

Have you met this question in a real interview?

Yes

Example

a = 11

b = 1

Return 100

LeetCode上的原题，请参见我之前的博客Add Binary。

class Solution {
public:
    /**
     * @param a a number
     * @param b a number
     * @return the result
     */
    string addBinary(string& a, string& b) {
        string res = "";
        int m = a.size() - , n = b.size() - , carry = ;
        while (m >=  || n >= ) {
            int p = m >=  ? a[m--] - '' : ;
            int q = n >=  ? b[n--] - '' : ;
            int sum = p + q + carry;
            res = to_string(sum % ) + res;
            carry = sum / ;
        }
        return carry ==  ? "" + res : res;
    }
};