## Problem Design a `GamepadTracker` that records sequences of button/axis inputs with timestamps and can replay them to check whether a recorded combo was input within a timing window. Support: ```python class GamepadTracker: def record(self, input_event: dict) -> None: # event = {"type": "button"|"axis", "id": str, "value": float, "ts": int} def detect_combo( self, combo: list[dict], # sequence of events to match window_ms: int # all events must occur within this window ) -> bool: def get_recent(self, duration_ms: int) -> list[dict]: ``` ## Example ``` tracker.record({"type": "button", "id": "A", "value": 1, "ts": 1000}) tracker.record({"type": "button", "id": "B", "value": 1, "ts": 1050}) tracker.record({"type": "button", "id": "A", "value": 1, "ts": 1200}) combo = [{"id": "A"}, {"id": "B"}] tracker.detect_combo(combo, window_ms=200) # -> True (A at 1000, B at 1050: both within 200ms) ``` ## Follow-ups 1. How do you handle axis inputs where the value must exceed a threshold (e.g., joystick > 0.8)? 2. What data structure enables efficient sliding-window combo detection as new events arrive? 3. How would you extend this to support approximate matching (one missed input allowed)?

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Gamepad Input Tracker: Parse and Replay Gamepad Input Sequences with Timing

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Problem Design a GamepadTracker that records sequences of button/axis inputs with timestamps and can replay them to check whether a recorded combo was input within a timing window. Support: Example Follow-ups How do you handle axis inputs where the value must exceed a threshold (e.g., joystick > 0.8)? What data structure enables efficient sliding-window combo detection as new events arrive? How would you extend this to support approximate matching (one missed input allowed)?

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This is a reported interview question from a jane street interview during the phone round.

It covers the following topics: Sliding Window, Coding, Phone, Onsite .

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Gamepad Input Tracker: Parse and Replay Gamepad Input Sequences with Timing

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