[LeetCode] 374 | Guess Number Higher or Lower | Python

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문제 링크: https://leetcode.com/problems/guess-number-higher-or-lower/

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문제

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 will tell you whether the number I picked is higher or lower than your guess.

You call a pre-defined API int guess(int num), which returns three possible results:

• -1: Your guess is higher than the number I picked (i.e. num > pick).
• 1: Your guess is lower than the number I picked (i.e. num < pick).
• 0: your guess is equal to the number I picked (i.e. num == pick).

Return the number that I picked.

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조건

• 1 <= n <=$2^{31}-1$
• 1 <= pick <= n

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내 풀이

Binary Search(이분탐색)으로 푼다.

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코드

# The guess API is already defined for you.
# @param num, your guess
# @return -1 if num is higher than the picked number
#          1 if num is lower than the picked number
#          otherwise return 0
# def guess(num: int) -> int:

class Solution:
    def guessNumber(self, n: int) -> int:
        left = 1
        right = n+1
        
        while left+1 < right:
            mid = (left + right) // 2
            
            if guess(mid) >= 0:
                left = mid
            else:
                right = mid
        
        return left