System design interview question
"Design a parking system for a large multi-storey car park. Cars enter, take a spot, and pay on exit based on how long they stayed. There are different spot sizes and rates, and the barrier must open quickly. Then tell me how it changes across 500 car parks."
This is the standard entry-level / warm-up design question, and it is chosen because it is small enough to finish. The signal is in whether the candidate produces clean abstractions (a pricing strategy that is not a pile of if statements), handles the obvious physical edge cases (lost ticket, barrier failure), and knows when to stop designing rather than over-engineering a car park into a distributed system.
On Practick another engineer interviews you live for 60 minutes on a question from this bank. They have the full interviewer guide beside the call: the answers to your clarifying questions, the numbers to hand out, a ladder of follow-ups and a scoring rubric. You get the model solution once the session settles. It is free: interview someone for an hour and you have earned your own.
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