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Code RoomEvent listener memory leak
MediumPrep Room Coding #4074

Event listener memory leak

Vibe & agenticAlgorithms & data structuresMid–Senior~17 min

This AI-written hook tracks window width for a responsive layout. After navigating between pages a few times the app slows down and console warns about updating an unmounted component. Identify the defect.

Implement
active_listener_count(lifecycle_events: list[str], has_cleanup: bool) → int
Examples
in[["mount","unmount","mount","unmount"],true]out0
in[["mount","unmount","mount","unmount"],false]out2
in[["mount"],true]out1
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.

0:00 of about 17 min

Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.