Design Ride Requests, Driver Matching, and Trip State

Design a ride-sharing system. Explain the core flow from requesting a ride through matching, pickup, completion, and recording the trip's outcome. ### Constraints Geographic scope, traffic, matching objective, pricing, payment, and service guarantees are unspecified. State a bounded baseline and clarify which features are required. Any concrete location-update interval, radius, or dispatch policy is an explicit assumption. ### Clarifying Questions - What geographic area and rider/driver volume must be supported? - Is matching based on distance, estimated pickup time, fairness, or another objective? - Can drivers receive several offers, and how long is an offer valid? - What are the rules for cancellation, stale locations, and lost connectivity? ```hint Make assignment a state transition Finding nearby drivers is different from ensuring that two riders cannot both acquire the same available driver. ``` ### What a Strong Answer Covers - Rider, driver, location, request, offer, and trip state models. - Candidate search, coordinated assignment, location freshness, and notification delivery. - Failure recovery, idempotency, geographic partitioning, and observable service behavior. ### Follow-up Questions - What if a driver accepts after an offer has expired? - How would you handle requests near the boundary between geographic partitions?