67. Add Binary

 1 class Solution {
 2 public:
 3     string addBinary(string a, string b) {
 4         string res;
 5         int carry = 0;
 6         int a_end = a.size()-1;
 7         int b_end = b.size()-1;
 8         while(a_end>=0||b_end>=0){
 9             int i = (a_end>=0 &&a[a_end]==‘1‘);
10             int j = (b_end>=0 &&b[b_end]==‘1‘);
11             int temp = i+j+carry;
12             if(temp>=2){
13                 res=to_string(temp-2)+res;
14                 carry =1;
15             }
16             else{
17                 res=to_string(temp)+res;
18                 carry =0;    
19             }
20             a_end--;
21             b_end--;
22            
23         }
24         if(carry)
25             res=‘1‘+res;
26         return res;
27     }
28 };