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Code RoomDating proximity matching
MediumPrep Room Coding #3530

Dating proximity matching

System designDistributed systemsMid–Senior~45 min

Design the proximity-matching backend for a dating app: a user sees nearby candidate profiles filtered by distance, age, gender preference, and other criteria, ranked by a relevance score. Users move (commuting, traveling) so their location changes; the candidate pool is ~50M profiles; queries must return in <150ms; and exact locations must NOT be exposed (showing '2 miles away' is fine, leaking precise coordinates is a safety problem). Describe the spatial index combined with multi-attribute filtering, how you protect exact location, and the freshness trade-off as users move.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.

Clarify5:00 left
Estimate5:00 planned
Design15:00 planned
Deep dive12:00 planned
Failure8:00 planned
0:00
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.