Number of Recent Calls 15 XP Easy

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Implement a RecentCounter that counts the number of requests made within the last 3000 milliseconds.

counter = RecentCounter()
counter.ping(1)      # 1 request in [1-3000, 1] → but range starts at max(0,1-3000)=0
                     # Requests in range: [1] → return 1
counter.ping(100)    # Requests in [-2900, 100] → [1, 100] → return 2
counter.ping(3001)   # Requests in [1, 3001] → [1, 100, 3001] → return 3
counter.ping(3002)   # Requests in [2, 3002] → [100, 3001, 3002] → return 3

A queue is perfect here:

Add each new timestamp to the queue
Remove timestamps that are older than t - 3000 from the front
Return the length of the queue
Since timestamps are always increasing, old ones are always at the front

The queue naturally maintains the sliding window of valid timestamps.

📋 Instructions

Implement the RecentCounter class. Test with ping(1), ping(100), ping(3001), ping(3002) and print each result.

Use a deque. In ping(t), append t, then while q[0] < t - 3000, popleft(). Return len(q).

🧪 Test Cases

Input

counter.ping(1)

Expected

1

Test case 1

Input

counter.ping(100)

Expected

2

Test case 2

Input

counter.ping(3001)

Expected

3

Test case 3

Input

counter.ping(3002)

Expected

3

Test case 4

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main.py

Hi! I'm Rex 👋

Output

Ready. Press ▶ Run or Ctrl+Enter.

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