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( )。

 1 #include "stdafx.h"
 2 #include <string>
 3 #include <iostream>
 4 #include <algorithm>
 5 class Solution
 6 {
 7 public:
 8     string addBinary(string a, string b)
 9     {
10         string result("");
11         reverse(a.begin(),a.end());//注意运算顺序的问题!!!
12         reverse(b.begin(),b.end());
13
14         auto ita = a.begin();
15         auto itb = b.begin();
16         int data1 = 0;
17         int data2 = 0;
18         int carry = 0;
19         int sum = 0;
20
21         while(ita != a.end() || itb != b.end())
22         {//从尾向前遍历
23             data1 = 0;
24             data2 = 0;
25             if(ita != a.end())
26             {
27                 data1 = *ita -‘0‘;
28                 ita++;
29             }
30             if(itb != b.end())
31             {
32                 data2 = *itb -‘0‘;
33                 itb++;
34             }
35             sum = data1+data2+carry;
36             //头插
37             result.insert(result.begin(),sum%2+‘0‘);//!!!格式问题
38             carry = sum/2;
39         }
40         if(carry== 1)
41             result.insert(result.begin(),‘1‘);
42
43         return result;
44     }
45 };
46 int main()
47 {
48     Solution sol;
49     cout << sol.addBinary(string("11"),string("1"))<<endl;
50     cout << sol.addBinary(string(""),string("1"))<<endl;
51     cout << sol.addBinary(string("111"),string("1111"))<<endl;
52     cout << sol.addBinary(string("111"),string("111"))<<endl;
53     cout << sol.addBinary(string(""),string(""))<<endl;
54     return 0;
55 }