Design an ATM that authenticates a card and PIN, and supports balance inquiry, cash withdrawal with denomination dispensing, and deposits, including session/state handling and hardware abstractions.
Design an ATM: it authenticates a card and PIN, then supports balance inquiry, cash withdrawal with denomination dispensing, and deposits, serving one customer session at a time. Model the card reader, cash dispenser, and bank backend as distinct collaborators.
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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