Code RoomRate limiter off-by-one
MediumPrep Room Coding #4197

Rate limiter off-by-one

Vibe & agenticAlgorithms & data structuresMid–Senior~15 min

An AI agent added rate limiting to a Go API gateway, claiming it 'allows up to N requests per sliding minute per client':

It passed a test that fires N requests and expects the (N+1)th to be blocked. What do you verify, and what's the real defect?

Implement
sliding_window_allow(request_times: list[int], limit: int, window_ms: int) → list[bool]
Examples
in[[0,100,200,300],2,1000]out[true,true,false,false]
in[[0,100,200,1050],2,1000]out[true,true,false,true]
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 15 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.