[LeetCode] Problem 933 - Number of Recent Calls

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Write a class RecentCounter to count recent requests.

It has only one method: ping(int t), where t represents some time in milliseconds.

Return the number of pings that have been made from 3000 milliseconds ago until now.

Any ping with time in [t - 3000, t] will count, including the current ping.

It is guaranteed that every call to ping uses a strictly larger value of t than before.

Example

Input: inputs = [“RecentCounter”,”ping”,”ping”,”ping”,”ping”], inputs = [[],[1],[100],[3001],[3002]]

Output: [null,1,2,3,3]

Note

Each test case will have at most 10000 calls to ping.
Each test case will call ping with strictly increasing values of t.
Each call to ping will have 1 <= t <= 10^9.

Code

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Queue<Integer> queue;

public RecentCounter() {
    queue = new LinkedList();
}

public int ping(int t) {
    queue.offer(t);

    while (queue.peek() < t - 3000)
        queue.poll();

    return queue.size();
}