LeetCode 374. Guess Number Higher or Lower

Problem Statement

(Source) 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.

Solution

Tags: Binary Search.

# The guess API is already defined for you.# @param num, your guess# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0# def guess(num):class Solution(object):    def guessNumber(self, n):        """        :type n: int        :rtype: int        """        lo, hi = 1, n        while lo <= hi:            mid = (lo + hi) >> 1            res = guess(mid)            if res == -1:                hi = mid - 1            elif res == 0:                return mid            else:                lo = mid + 1