Add Binary

 1     string addBinary(string a, string b) {
 2     //4ms
 3     const char * shortStr = (a.size()<=b.size())?a.c_str():b.c_str();
 4     const char * longStr = (a.size()>b.size())?a.c_str():b.c_str();
 5     int lenShort = strlen(shortStr);
 6     int lenLong = strlen(longStr);
 7     
 8     string s="";
 9     int temp;
10     int flag = 0;
11     for (int i = 0; i < lenShort; ++i)
12     {
13         temp = shortStr[lenShort-1-i]-‘0‘+longStr[lenLong-1-i]-‘0‘+ flag;
14         flag = temp/2;
15         s.insert(0,1,‘0‘+temp%2);
16     }
17    
18     for (int i = lenLong-1-lenShort; i >=0; --i)
19     {
20         temp = longStr[i]-‘0‘+flag;
21         flag = temp/2;
22         s.insert(0,1,‘0‘+temp%2);
23     }
24     
25     if (flag == 1)
26         s.insert(0,1,‘1‘);
27     return s;
28     }