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!


Basic Binary Search Problem:

class Solution(object):
    def guessNumber(self, n):
        """
        :type n: int
        :rtype: int
        """
        low, high = 1, n
        
        while low <= high:
            mid = (low + high)//2
            ans = guess(mid)
            if ans == 1:
                low = mid + 1
            elif ans == -1:
                high = mid - 1
            else:
                return mid