Guess Number Higher Or Lower

Guess Number Higher Or Lower binary search

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.

Guess Number Higher Or Lower Solution

public class GuessNumberHigherOrLower 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) {
                left = mid + 1;
            } else {
                right = mid;
            }
        }

        return -1;
    }
}

Last modified October 4, 2020