No.67 Add Binary

No.67 Add Binary

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

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

　　与No.2 Add Two Numbers的思路非常相似，不同在：对其进行运算时，其实是要逆向相加的!!!因为边界控制的原因，可先将字符串逆序reverse( )。

#include "stdafx.h"
#include <string>
#include <iostream>
#include <algorithm>
class Solution
{
public:
    string addBinary(string a, string b)
    {
        string result("");
        reverse(a.begin(),a.end());//注意运算顺序的问题!!!
        reverse(b.begin(),b.end());

        auto ita = a.begin();
        auto itb = b.begin();
        int data1 = 0;
        int data2 = 0;
        int carry = 0;
        int sum = 0;

        while(ita != a.end() || itb != b.end())
        {//从尾向前遍历
            data1 = 0;
            data2 = 0;
            if(ita != a.end())
            {
                data1 = *ita -'0';
                ita++;
            }
            if(itb != b.end())
            {
                data2 = *itb -'0';
                itb++;
            }
            sum = data1+data2+carry;
            //头插
            result.insert(result.begin(),sum%2+'0');//!!!格式问题
            carry = sum/2;
        }
        if(carry== 1)
            result.insert(result.begin(),'1');

        return result;
    }
};
int main()
{
    Solution sol;
    cout << sol.addBinary(string("11"),string("1"))<<endl;
    cout << sol.addBinary(string(""),string("1"))<<endl;
    cout << sol.addBinary(string("111"),string("1111"))<<endl;
    cout << sol.addBinary(string("111"),string("111"))<<endl;
    cout << sol.addBinary(string(""),string(""))<<endl;
    return 0;
}