Prep RoomSign inStart free
Code RoomCSV row count memory overflow
MediumPrep Room Coding #4422

CSV row count memory overflow

Vibe & agenticDistributed systemsMid–Senior~16 min

This Lambda (Python) was generated to count rows in a CSV that S3 events deliver. It works for sample files and crashes with out-of-memory on real uploads. Identify the bug and the fix.

Implement
count_csv_rows_streaming(chunks: list[str], has_header: bool) → int
Examples
in[["a,b\n1,2\n3,4\n"],true]out2
in[["a,b\n1",",2\n3,","4"],false]out3
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 16 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.