The set and get parts were fine, standard hashmap stuff.
Start by clarifying the requirements and constraints, especially the amortized O(1) for setAll. Then propose a design using a versioned timestamp approach where each key stores a version and the store maintains a global version with a default value. Finally, discuss implementation details, trade-offs, and potential edge cases.
Pro tip: Emphasize that setAll is O(1) by lazily updating keys only when accessed, and highlight that this design is used in real systems like Redis. Also, mention that you would consider thread-safety for production use.
Ask about expected data types, concurrency needs, memory constraints, and whether setAll should affect keys set before or after the call. Confirm that amortized O(1) means occasional O(n) operations are acceptable if rare.
Propose a hash map for key-value storage, where each entry stores the value and a version number. Maintain a global version counter and a global default value. On setAll, increment the global version and update the default value.
For set(key, value), store the value with the current global version. For get(key), if the key's version is less than the global version, return the global default; otherwise return the stored value. For setAll(value), just update the global version and default value.
Explain that set and setAll are O(1), and get is O(1) amortized because it may need to update the key's version and value to the global default (lazy update). Discuss memory overhead of storing versions and potential for stale entries.
Mention handling of missing keys, concurrency (e.g., using locks or atomic operations), and possible optimizations like periodic cleanup of stale entries. Also, consider if setAll should affect future keys (it does by design).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.