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Leetcode 1396. Design Underground System

Design a system that records passenger check-ins and check-outs and returns the average direct travel time between two stations. The core challenge is maintaining active check-ins per passenger id and aggregated travel-time statistics (sum and count) per station-pair to answer getAverageTime queries efficiently.

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Axon

Ramp


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Late October, 2025

Axon

Senior

Police officers report their timed GPS location to a dispatch center. Implement a function for the dispatch center to find an officer's location closest to a given time.

Late July, 2025

Ramp

Mid-level

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