【LeetCode】 374. Guess Number Higher or Lower

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I'll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower 1 : My number is higher 0 : Congrats! You got it!

Example:

n = 10, I pick 6.Return 6.

/* 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 start = 0, end = n;        while (start < end) {            int mid = start + (end - start) / 2;            if (guess(mid) == 0) {                return mid;            } else if (guess(mid) == 1) {                start = mid + 1;            } else {                end = mid;            }        }        return start;    }}