In-Memory DB: Track per-key operation counts and return Top N keys

Problem: In-Memory DB Variant — Count operations for each key and return the Top N keys Build a simplified in-memory database whose records are stored by key. For this version, each operation performed on a key must increase that key's operation counter by one. The database must also provide a way to retrieve the N keys with the greatest operation counts. Required functionality Keep an in-memory representation that supports the database operations on a key; the precise…