LeetCode 362. Design Hit Counter 桶-优快云博客

本文介绍了一种高效的设计方案，用于实现在过去5分钟内的点击次数计数器。通过使用缓存解法，文章详细解释了如何利用时间戳和命中次数列表来跟踪并返回最近5分钟内的总点击数，同时提供了代码实现。

Design a hit counter which counts the number of hits received in the past 5 minutes.

Each function accepts a timestamp parameter (in seconds granularity) and you may assume that calls are being made to the system in chronological order (ie, the timestamp is monotonically increasing). You may assume that the earliest timestamp starts at 1.

It is possible that several hits arrive roughly at the same time.

Example:

HitCounter counter = new HitCounter();

// hit at timestamp 1.
counter.hit(1);

// hit at timestamp 2.
counter.hit(2);

// hit at timestamp 3.
counter.hit(3);

// get hits at timestamp 4, should return 3.
counter.getHits(4);

// hit at timestamp 300.
counter.hit(300);

// get hits at timestamp 300, should return 4.
counter.getHits(300);

// get hits at timestamp 301, should return 3.
counter.getHits(301);

Follow up:
What if the number of hits per second could be very large? Does your design scale?

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直接滑动，最好用个deque，deque不会写可以用个dict，偷懒发现塞到一个list也可以过：

code略

缓存解法：

class HitCounter:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.times,self.hits = [0 for i in range(300)],[0 for i in range(300)]
        

    def hit(self, timestamp: int) -> None:
        """
        Record a hit.
        @param timestamp - The current timestamp (in seconds granularity).
        """
        t = timestamp % 300
        if (self.times[t] == timestamp):
            self.hits[t] += 1
        else:
            self.hits[t] = 1
            self.times[t] = timestamp

    def getHits(self, timestamp: int) -> int:
        """
        Return the number of hits in the past 5 minutes.
        @param timestamp - The current timestamp (in seconds granularity).
        """
        return sum(self.hits[i] for i in range(300) if timestamp-self.times[i] < 300)