leetcode

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

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

字符串相加，不难

个人思路：

1，尾部对齐，然后逐位相加，flag记为进位

代码：

#include <string>

using namespace std;

class Solution {
public:
    string addBinary(string a, string b) {
        if (a.empty())
        {
            return b;
        }
        if (b.empty())
        {
            return a;
        }

        int aLen = a.length();
        int bLen = b.length();
        int i = aLen - 1, j = bLen - 1;
        int flag = 0; //进位
        int temp, ai, bj;
        string result;

        for (; i >= 0 || j >= 0; --i, --j)
        {
            ai = i >= 0 ? (a[i] - '0') : 0;
            bj = j >= 0 ? (b[j] - '0') : 0;

            temp = ai + bj + flag;
            flag = temp > 1 ? 1 : 0;
            temp = temp - flag * 2;

            result.insert(result.begin(), temp + '0');
        }

        if (flag)
        {
            result.insert(result.begin(), '1');
        }

        return result;
    }
};