ds-forge — interview trainer

Problem

Build a HomeSearch over Home records (id, price, beds). search(minPrice, maxPrice, minBeds, sort, page, size) returns one page of matching homes. Filter to homes whose price is within [minPrice, maxPrice] inclusive and whose beds are at least minBeds; sort by price ascending ("price_asc") or descending ("price_desc"); then paginate with a 0-based page index and a page size. Order the filter -> sort -> paginate so the page is a slice of the fully sorted result, not of the raw list.

iThe deal with the pair partner

The AI is deliberately fallible — it gives hints, not solutions, and sometimes proposes wrong code. It cannot touch your editor. Paste what you choose, then Run. Anything AI-derived stays UNVERIFIED until your tests go green.

Self-check

☐filter keeps only homes with minPrice <= price <= maxPrice (both bounds inclusive) and beds >= minBeds
☐sort honors price_asc vs price_desc, with a deterministic tie-break (id ascending) so equal prices have a stable order
☐pagination slices the SORTED, FILTERED list: page is 0-based, the slice is [page*size, page*size + size)
☐an out-of-range page (past the end) returns an empty list rather than throwing
☐you named the cost (this scans + sorts every call) and what you would add for scale (a pre-sorted or indexed structure, a stable cursor instead of offset pages)

Hints / what this doesn't test

This is an Opendoor-flavored applied problem: the bread-and-butter "search results page" — filter a catalog, order it, hand back one page. Restate the contract before you touch code — "So the price range is inclusive on both ends, beds is a floor not an exact match, and the page is a slice of the sorted, filtered list — I sort the whole match set first, then cut the page out of it?" That ordering is the whole problem; paginating before sorting is the classic wrong answer.

What this problem does not test (say so out loud): multi-field sort keys (price then beds), full-text or geo filters, an upsert/dedup path, and a stable cursor (keyset) for pagination are all out of scope here — but a senior names that offset-based paging re-scans and re-sorts the whole catalog every call, that results can shift under the user if the catalog mutates between pages, and that a pre-sorted per-key index or a cursor is the real scaling move.

Solution.javaauto-runs ~0.8s after you pause

unverifiedEdited since last clean run — run to verify.

Tests

○ Not run yet — edit the code or press Run

○filter_by_price_range
○filter_by_beds
○sort_price_desc
○pagination_page_2
+ 2 hidden tests — revealed once the visible ones pass

Pair partner (병신 모드 · 버그 잡기)

gpt-4o-mini

Ask for a skeleton or a test plan — not the answer. Then implement the core yourself and come back for edge cases. Remember: the partner is fallible. Verify everything by running it.

The partner sees your editor but cannot change it. Copy any suggestion in by hand, then Run to verify.

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