CodingMediumcod-g223

Subject Stream processingLevel Mid–Senior~25 minCommon in Distributed systems interviewsIndustries Software development

Question

A stream may deliver the same message more than once. Given a list of (msg_id, payload) tuples in arrival order, return the payloads of only the first occurrence of each msg_id, in arrival order, as a list. Subsequent duplicates of an already-seen id are dropped regardless of payload. The input may be empty.

Implement

dedup_stream(messages: list[tuple]) → list

Examples

in[[[1,"a"],[2,"b"],[1,"c"]]]out["a","b"]

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.