[LeetCode] Add Binary

 1 class Solution {
 2 public:
 3     string addBinary(string a, string b) {
 4         string result;
 5         if (a.size() == 0 || b.size() == 0) {
 6             return a.size() == 0 ? b : a;
 7         }
 8         
 9         int carry  = 0;
10         int i = a.size() - 1;
11         int j = b.size() - 1;
12         while (i >= 0 || j >= 0) {
13             const int a_val = i >= 0 ? a[i--] - ‘0‘: 0;
14             const int b_val = j >= 0 ? b[j--] - ‘0‘: 0;
15             int temp_sum = a_val + b_val + carry;
16             result.push_back((temp_sum % 2) + ‘0‘);
17             carry = temp_sum / 2;
18         }
19         
20         if (carry == 1) result.push_back(‘1‘);
21         reverse(result.begin(), result.end());
22         return result;
23     }
24 };