Maps autocomplete
Design a search autocomplete service for a maps app that suggests places as the user types. Scale: 500M daily active users, p99 under 60ms per keystroke, a corpus of ~200M places that changes slowly (new businesses, closures), but suggestions must be ranked by the user's current geolocation and recent search history.
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.
Clarify4:30 left
Estimate4:30 planned
Design13:30 planned
Deep dive10:30 planned
Failure7:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.