/* The guess API is defined in the parent class GuessGame. @param num, your guess @return -1 if my number is lower, 1 if my number is higher, otherwise return 0 int guess(int num); */ public class Solution extends GuessGame { public int guessNumber(int n) { int beg = 1, end = n; while (beg <= end) { int mid = beg + (end - beg) / 2; int val = guess(mid); if (val == -1) { end = mid - 1; } else if (val == 1) { beg = mid + 1; } else { return mid; } } return beg; } }