leetcode-go/leetcode/easy/374.guess-number-higher-or-lower.java

/* 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;
    }
}