Implement a service that accepts a message only when at least ten seconds have elapsed since the last accepted occurrence of that same message, keeping independent histories per message.
Before you code
Decide how to store the last accepted timestamp per message and confirm that rejected requests leave that timestamp unchanged before handling ordering or growth.
Hints
- Keep a map from each message to its last accepted timestamp.
- A rejection must not move the timestamp forward, or repeated attempts postpone acceptance forever.
- At exactly ten seconds the message is accepted, so compare with greater-or-equal rather than strictly greater.
Production & complexity notes
When solving Implement a Time-Based Logger Rate Limiter on LeetCode (easy), always state your loop or recursion invariant before writing code. Verify how your chosen data structure behaves on degenerate inputs (single-element inputs, all-duplicate keys, strictly monotonic sequences, or maximum constraint sizes up to $10^5$ elements). In production interviews, pair your implementation with an explicit time and auxiliary space complexity proof, explain why alternative brute-force approaches violate the latency budget, and trace how cache locality and memory allocation overhead affect wall-clock throughput on real hardware. Review the step-by-step memory trace in Cache-Conscious Data Structures: Alignment, False Sharing, and Structure of Arrays to reinforce the underlying pattern.
What it practices
Per-key throttle state with last-accepted timestamps and rejection-safe updates, from Turning a key into a slot.