Design a vending machine that manages inventory, accepts money, supports product selection and cancellation, returns change, and enforces a clear transaction state machine.
Design a vending machine that tracks products and stock, accepts supported denominations, lets a user select or cancel, dispenses only after sufficient payment, and returns exact change safely.
Work in the provided coding workspace while explaining your decisions to the live interviewer. Validation may use inline tests, examples, comments, or a verbal walkthrough.
Practice this problem in the live coding workspace while the interviewer probes your clarification, implementation, trade-offs, and validation.
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