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933. Number of Recent Calls

3 May 2025·115 words·1 min· loading

Table of Contents

Table of Contents

Solution
#

Use “deque” data structure to keep track of recent ping times.
Each time ping(t) is called, add t to the end of the deque and remove elements from the front until the first element is greater than or equal to t - 3000.

class RecentCounter {

    private final Deque<Integer> q = new ArrayDeque<>();

    public RecentCounter() {

    }

    public int ping(int t) {
        while (q.peekFirst() != null && q.peekFirst() < t - 3000) {
            q.pollFirst();
        }
        q.addLast(t);
        return q.size();
    }
}

class RecentCounter() {

    private val q = ArrayDeque<Int>()

    fun ping(t: Int): Int {
        while (q.firstOrNull()?.let { it < t - 3000 } == true) {
            q.removeFirst()
        }
        q.add(t)
        return q.size
    }

}