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可怜的小猪

有 buckets 桶液体,其中 正好有一桶 含有毒药,其余装的都是水。它们从外观看起来都一样。为了弄清楚哪只水桶含有毒药,你可以喂一些猪喝,通过观察猪是否会死进行判断。不幸的是,你只有 minutesToTest 分钟时间来确定哪桶液体是有毒的。 喂猪的规则如下: 选择若干活猪进行喂养 可以允许小…

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代码语言

hub

3

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困难 · 状态·转移·动态规划

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答案摘要

class Solution: def poorPigs(self, buckets: int, minutesToDie: int, minutesToTest: int) -> int:

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题目描述

buckets 桶液体,其中 正好有一桶 含有毒药,其余装的都是水。它们从外观看起来都一样。为了弄清楚哪只水桶含有毒药,你可以喂一些猪喝,通过观察猪是否会死进行判断。不幸的是,你只有 minutesToTest 分钟时间来确定哪桶液体是有毒的。

喂猪的规则如下:

  1. 选择若干活猪进行喂养
  2. 可以允许小猪同时饮用任意数量的桶中的水,并且该过程不需要时间。
  3. 小猪喝完水后,必须有 minutesToDie 分钟的冷却时间。在这段时间里,你只能观察,而不允许继续喂猪。
  4. 过了 minutesToDie 分钟后,所有喝到毒药的猪都会死去,其他所有猪都会活下来。
  5. 重复这一过程,直到时间用完。

给你桶的数目 bucketsminutesToDieminutesToTest ,返回 在规定时间内判断哪个桶有毒所需的 最小 猪数 。

 

示例 1:

输入:buckets = 1000, minutesToDie = 15, minutesToTest = 60
输出:5

示例 2:

输入:buckets = 4, minutesToDie = 15, minutesToTest = 15
输出:2

示例 3:

输入:buckets = 4, minutesToDie = 15, minutesToTest = 30
输出:2

 

提示:

  • 1 <= buckets <= 1000
  • 1 <= minutesToDie <= minutesToTest <= 100
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解题思路

方法一

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class Solution:
    def poorPigs(self, buckets: int, minutesToDie: int, minutesToTest: int) -> int:
        base = minutesToTest // minutesToDie + 1
        res, p = 0, 1
        while p < buckets:
            p *= base
            res += 1
        return res
speed

复杂度分析

指标
时间Depends on the final approach
空间Depends on the final approach
psychology

面试官常问的追问

外企场景
  • question_mark

    Look for the candidate's understanding of state transition problems in dynamic programming.

  • question_mark

    Evaluate how well the candidate applies combinatorics to optimize the problem solution.

  • question_mark

    Check for a clear explanation of how binary representation is used to model outcomes.

warning

常见陷阱

外企场景
  • error

    Not considering the optimal distribution of pigs across buckets, leading to unnecessary pigs for fewer buckets.

  • error

    Overcomplicating the problem by not using binary or combinatorial representations effectively.

  • error

    Failing to account for the time constraints and misjudging how many pigs are needed based on the number of test rounds.

swap_horiz

进阶变体

外企场景
  • arrow_right_alt

    Increasing the number of buckets or test time constraints to assess scalability of the approach.

  • arrow_right_alt

    Allowing pigs to be reused across multiple tests, which changes the dynamic of how the problem is solved.

  • arrow_right_alt

    Introducing more than one poisonous bucket, requiring more sophisticated state transition models.

help

常见问题

外企场景

可怜的小猪题解:状态·转移·动态规划 | LeetCode #458 困难