Design an in-memory hotel booking system

Design a **hotel booking system** that supports reservations **without using any database**. You may only use **in-memory data structures**. ### Requirements Define APIs/data structures to support at least: - Add hotels, room types, and room inventory (or individual rooms) - Search availability for a date range (check-in, check-out) - Create a booking (reserve room(s)) - Cancel a booking - Prevent double-booking under concurrent requests ### Constraints/notes - All state is in memory (assume a single process unless you choose to extend to multiple nodes). - Clarify assumptions (e.g., time zones, check-out exclusivity, maximum date horizon). - Discuss complexity trade-offs and how you would handle concurrency.