【字符串】67. 二进制求和

 1 class Solution {
 2 public:
 3     string addBinary(string a, string b) 
 4     {
 5         int la = a.size();
 6         int lb = b.size();
 7         
 8         string sum = la > lb ? a : b;
 9         int overflow = 0;
10 
11         for (int i = 0; i < sum.size(); i++)
12         {
13             char ca = i < la ? a[la - i - 1] : ‘0‘;
14             char cb = i < lb ? b[lb - i - 1] : ‘0‘;
15             int bit = ca - ‘0‘ + cb - ‘0‘ + overflow;
16             overflow = bit / 2;
17             sum[sum.size() - i - 1] = bit % 2 + ‘0‘;
18         }
19         
20         if (overflow)
21         {
22             sum = ‘1‘ + sum;
23         }
24 
25         return sum;
26 
27     }
28 };