Code Room
CodingMediumcod-g1280
Subject HeapsLevel Entry–Mid~15 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

A log pipeline collects error codes from a web service in the order they occurred. Given that ordered list and an integer k, return the k codes that occurred most often, highest count first. When two codes have equal counts, the one whose first occurrence came earlier in the log wins the earlier spot. Assume 1 <= k <= number of distinct codes. Example: codes = ["504", "500", "504", "500", "404"], k = 2 gives ["504", "500"] — both occur twice, and "504" appeared first.

Implement
frequent_error_codes(codes: list[str], k: int) → list[str]
Examples
in[["504","500","504","500","404"],2]out["504","500"]
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.

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.