Web Logger

最新推荐文章于 2024-04-14 09:38:01 发布

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本文介绍如何实现一个Web日志记录器，它包含两个方法：记录指定时间戳的点击，并获取过去5分钟内的点击次数。方法调用按时间戳升序进行，可以使用Deque数据结构有效地处理这些操作。

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Implement a web logger, which provide two methods:

hit(timestamp), record a hit at given timestamp.
get_hit_count_in_last_5_minutes(timestamp), get hit count in last 5 minutes.

the two methods will be called with non-descending timestamp (in sec).

Example

Example 1:

Input:
  hit(1);
  hit(2);
  get_hit_count_in_last_5_minutes(3);
  hit(300);
  get_hit_count_in_last_5_minutes(300);
  get_hit_count_in_last_5_minutes(301);
Output:
  2
  3
  2

Example 2:

Input:
  hit(1)
  hit(1)
  hit(1)
  hit(2)
  get_hit_count_in_last_5_minutes(3)
  hit(300)
  get_hit_count_in_last_5_minutes(300)
  get_hit_count_in_last_5_minutes(301)
  get_hit_count_in_last_5_minutes(302)
  get_hit_count_in_last_5_minutes(900)
  get_hit_count_in_last_5_minutes(900)
Output:
  4
  5
  2
  1
  0
  0

Notice

The unit of timestamp is seconds.

The call to the function is in chronological order, that is to say, timestamp is in ascending order.

思路：前面要弹出去，后面要加进来，用deque就可以解决；注意deque = new ArrayDeque<Integer>(); peekFirst(), pollFirst();

这题其实用queue做也可以，queue的poll, peek,offer 也可以做；

public class WebLogger {
    private Deque<Integer> deque;
    public WebLogger() {
        deque = new ArrayDeque<Integer>();
    }

    /*
     * @param timestamp: An integer
     * @return: nothing
     */
    public void hit(int timestamp) {
        // 这里也可以维护一个300size的queue；
        while(!deque.isEmpty() && timestamp - deque.peekFirst() >= 300) {
            deque.pollFirst();
        }
        deque.offer(timestamp);
    }

    /*
     * @param timestamp: An integer
     * @return: An integer
     */
    public int get_hit_count_in_last_5_minutes(int timestamp) {
        // 注意get_hit_count的时候，并没有往queue里面加东西；
        while(!deque.isEmpty() && timestamp - deque.peekFirst() >= 300) {
            deque.pollFirst();
        }
        return deque.size();
    }
}