Persistent Key-Value Store

Persistent Key-Value Store Design and implement a persistent key-value store. Functional requirements Support the following operations: put(key, value): insert or overwrite a key-value pair get(key): return the value for key; if missing, return empty/NOT_FOUND delete(key): delete key; ignore if it does not exist Persistence: after process restart / re-initialization, previously written data must still be readable (recover from disk). I/O format (pick one as specified by interviewer) Command stream (stdin): one command per line, e.g. PUT <key> <value> GET <key> DEL <key> Print one line for each GET. API: implement put/get/delete, and provide open(path) / close() or a constructor that takes a data file path. Constraints and edge cases (clarify with interviewer if unspecified) Keys/values are strings or byte sequences. Number of operations can be large; aim for reasonable time complexity. You may use an append-only log and/or snapshots to support recovery. Example Input: PUT a 1 PUT b hello GET a DEL a GET a GET b Output: 1 NOT_FOUND hello Suggested scale assumptions Operations N up to 1e5 Key/value length: 1 ~ 1e3 Example Input PUT a 1 PUT b hello GET a DEL a GET a GET b Output 1 NOT_FOUND hello