LeetCode #362 - Design Hit Counter

最新推荐文章于 2022-12-29 21:27:45 发布

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本文介绍了一种设计思路，用于实现一个能够记录并返回过去5分钟内点击次数的点击计数器。通过使用队列数据结构，可以有效管理点击事件，并在请求时快速计算出特定时间窗口内的点击总数。

题目描述：

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?

计算过去五分钟内的点击数，同时也可以指定某一秒钟进行点击。那么应该维护一个队列，存储每一次点击的时间，那么新加入一次点击，就把队首所有超出时间范围的点击都删除。

class HitCounter {
public:
    /** Initialize your data structure here. */
    HitCounter() {}
    
    /** Record a hit.
        @param timestamp - The current timestamp (in seconds granularity). */
    void hit(int timestamp) {
        q.push(timestamp);
    }
    
    /** Return the number of hits in the past 5 minutes.
        @param timestamp - The current timestamp (in seconds granularity). */
    int getHits(int timestamp) {
        int start=timestamp-300;
        while(!q.empty()&&q.front()<=start) q.pop();
        return q.size();
    }
    
private:
    queue<int> q;
};