The createAccount and deposit parts were fine, pretty mechanical.
Clarify the API contract and edge cases first, then design a simple in-memory data structure (e.g., a hash map) that supports O(1) lookups and updates. Implement each operation with explicit validation and return values, and discuss how you would test the system and extend it for concurrency or persistence.
Pro tip: Mention that you would use a lock or transactional semantics to ensure atomicity in transfer, especially if the system is concurrent, and discuss how timestamps could be used for auditing or ordering.
Ask questions to confirm the expected behavior for each operation, including return values, error conditions, and whether timestamps affect logic or are just for logging.
Choose a data structure (e.g., hash map) to store accounts and balances, and define the method signatures with clear return types and error handling.
Write code for createAccount, deposit, and transfer, ensuring each checks preconditions (e.g., account existence, sufficient funds) and returns the specified values.
Walk through test cases for success and failure scenarios, including missing accounts, duplicate creation, same-account transfer, and insufficient funds.
Mention how to handle concurrency (e.g., locks), persistence, and additional features like transaction history, showing awareness of system design.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.