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 :

Input: n = 10, pick = 6
Output: 6



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



From 1 to n 


Target is  x between 1 and n 

Left = 1
Right = n

-1 : My number is lower
你猜大了

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int left = 1;
        int right = n;
        while(left < right){
            int mid = left + (right - left) / 2;
            if(guess(mid) == 0){
                return mid;
            }else if(guess(mid) < 0){
                right = mid - 1;
            }else{
                left = mid + 1;
            }
        }
        return left;
        
    }
}