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Code RoomMemoized child re-renders on handler
MediumPrep Room Coding #4080

Memoized child re-renders on handler

Vibe & agenticAlgorithms & data structuresMid–Senior~16 min

A teammate memoized a heavy child with React.memo to stop re-renders, and an AI 'helped' by passing the handler below. The child still re-renders on every parent render. Why, and what's the proper fix?

Implement
child_render_count(prop_kinds: list[str], parent_renders: int) → int
Examples
in[["inline-function"],5]out5
in[["usecallback-stable"],5]out1
in[[],5]out1
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.