Implement a KV Store with Shutdown/Restore

Problem: Implement a KV Store with Shutdown/Restore Implement a key-value store that supports the following 4 operations: set(key, value): write string value to string key. get(key): return the value for key; if it does not exist, return NULL (or empty string—must be defined). shutdown(): simulate service shutdown. After shutdown, the data must be recoverable. restore(): called on service restart to recover the state saved by the last shutdown(). Constraints & Requirements key and value are strings. Multiple shutdown() / restore() cycles may occur. After restore(), the state must match exactly what it was at the last shutdown(). Explain how shutdown() persists data (e.g., write a file / serialize to disk). Follow-up (size limit) If the KV store has a size limit (e.g., max number of entries or max total bytes), what should happen when a set would exceed the limit? Implement a reasonable policy (e.g., LRU eviction, LFU eviction, reject writes) and justify it. I/O format (for evaluation) Read a sequence of operations from stdin, execute them in order, and print one line for each get. Line 1: integer n, number of operations Next n lines, each is one command: SET key value GET key SHUTDOWN RESTORE Scale 1 <= n <= 2 * 10^5 key/value length <= 100 Output For each GET: print the stored value if present otherwise print NULL Example Input 10 SET a 1 GET a SHUTDOWN SET a 2 GET a RESTORE GET a SET b 3 GET b GET c Output 1 2 1 3 NULL