isrepeat

 1 #include 
 2 bool isrepeat(char *source)
 3 {
 4     long long bits[4] = {0};
 5     int i = 0;
 6     while(source[i]){
 7         if(bits[source[i]/64]&(1<<(source[i]%64)))
 8             return true;
 9         else
10             bits[source[i]/64] ^= (1<<(source[i]%64));
11         i++;
12     }
13     return false;
14 }