Start by clarifying requirements and defining the API contract, including data structures and error handling. Then design the core logic for each operation, ensuring atomicity and timestamp handling. Finally, discuss trade-offs, edge cases, and potential extensions.
Pro tip: Emphasize idempotency and concurrency control, as real banking systems require these to prevent duplicate transactions and race conditions. Mentioning these shows you think beyond basic functionality.
Ask questions to understand expected inputs, outputs, and constraints (e.g., timestamp format, account ID uniqueness, error handling). Define the API endpoints and their signatures.
Choose appropriate data structures (e.g., hash map for accounts) and consider persistence, concurrency, and scalability. Discuss in-memory vs. database-backed storage.
Write pseudocode or actual code for createAccount, deposit, and transfer. Ensure each validates inputs, handles timestamps, and returns False/None on errors.
Consider scenarios like duplicate account creation, insufficient funds, invalid timestamps, and concurrent transfers. Implement locks or transactions to maintain consistency.
Talk about design decisions (e.g., eventual consistency vs. strong consistency) and potential improvements like audit logs, idempotency keys, or rate limiting.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.