Guess number quickly

Similar Problems:

- CheatSheet: Leetcode For Code Interview
- CheatSheet: Common Code Problems & Follow-ups
- Tag: #game, #monotonicfunc, #binarysearch

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.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

## https://code.dennyzhang.com/guess-number-higher-or-lower ## Basic Ideas: binary search ## 1 1 1 0 -1 -1 -1 ## Complexity: Time O(log(n)), Space O(1) # 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 """ left, right = 1, n while left <= right: mid = int(left + (right-left)/2) v = guess(mid) if v == 0: return mid elif v == 1: left = mid + 1 else: right = mid - 1 return None