1 /* The guess API is defined in the parent class GuessGame. 2    @param num, your guess 3    @return -1 if my number is lower, 1 if my number is higher, otherwise return 0 4       int guess(int num); */ 5  6 public class Solution extends GuessGame { 7     public int guessNumber(int n) { 8         int start = 1, end = n; 9         while (start < end) {10             int mid = start + (end - start)/2;11             if (guess(mid) == 0) {12                 return mid;13             } else if (guess(mid) == 1) {14                 start = mid + 1;15             } else {16                 end = mid - 1;17             }18         }19         return start;20     }21 }