README.md

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

Solutions (Python)

1. 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
        """
        l, r = 1, n
        while l <= r:
            m = (l + r) // 2
            res = guess(m)
            if res == 0:
                return m
            elif res == 1:
                l = m + 1
            elif res == -1:
                r = m - 1