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Code RoomReliable UDP ack collision
HardPrep Room Coding #4281

Reliable UDP ack collision

Vibe & agenticAlgorithms & data structuresSenior–Staff~22 min

An AI implemented this retransmit/ack loop in Go for a reliable-UDP control channel. Under a flaky link it both wedges and duplicates work. Identify the protocol state-machine bug(s), the scenario that triggers each, and the fix.

Implement
reliable_send_result(seq: int, events: list[int], max_retries: int) → str
Examples
in[7,[7],3]out"acked"
in[7,[-1,-1,7],3]out"acked"
in[7,[-1,-1,-1,-1],3]out"gave_up"
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 22 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.