Room type hierarchy in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding inheritance in room type hierarchy

Consider a room type hierarchy where Room is the base class, and Bedroom and ConferenceRoom inherit from it. Which statement best describes the relationship?

A Room inherits properties from Bedroom and ConferenceRoom.

B Bedroom and ConferenceRoom are unrelated to Room and do not share any properties.

C Bedroom and ConferenceRoom share common properties from Room and add their own specific features.

D Room is a subtype of Bedroom and ConferenceRoom.

💡 Hint

Think about how inheritance works in object-oriented design.

In a hierarchy, the base class (Room) provides common properties. Subclasses (Bedroom, ConferenceRoom) inherit these and add their own.

❓ Architecture

intermediate

Designing a scalable room type hierarchy

You need to design a system to manage different room types in a hotel. Which design choice best supports adding new room types without changing existing code?

A Use an abstract Room class with subclasses for each room type implementing specific behaviors.

B Create a single Room class with many conditional statements to handle all room types.

C Duplicate code for each room type in separate classes without inheritance.

D Use global variables to store room type information and behaviors.

💡 Hint

Consider the Open/Closed Principle in software design.

An abstract base class with subclasses allows adding new room types by creating new subclasses, avoiding changes to existing code.

❓ scaling

advanced

Handling multiple room features in hierarchy

In a hotel system, rooms can have multiple features like 'hasProjector', 'hasBalcony', or 'isSoundproof'. What is the best way to design the room type hierarchy to handle these features efficiently?

A Create a subclass for every combination of features (e.g., BalconyConferenceRoom).

B Add all possible features as boolean fields in the base Room class.

C Ignore features and handle them only in the booking system.

D Use composition by creating feature classes and assign them to rooms instead of deep inheritance.

💡 Hint

Think about avoiding class explosion and promoting flexibility.

Composition allows flexible assignment of features to rooms without creating many subclasses for every feature combination.

❓ tradeoff

advanced

Tradeoffs between inheritance and composition in room types

Which statement best describes a tradeoff when choosing inheritance over composition for room type features?

A Inheritance always uses less memory than composition.

B Inheritance is simpler but less flexible; composition is more flexible but can be more complex to implement.

C Composition cannot represent shared behavior, inheritance can only represent shared data.

D Inheritance allows dynamic feature changes at runtime, composition does not.

💡 Hint

Consider flexibility and complexity in design patterns.

Inheritance is straightforward but rigid; composition offers flexibility by allowing dynamic feature assignment but requires more design effort.

❓ estimation

expert

Estimating storage needs for room type hierarchy

A hotel has 10,000 rooms with 5 main room types and 20 optional features. Each room stores its type and features. If each feature is stored as a boolean and the room type as an integer, approximately how much storage is needed to store all room type and feature data for all rooms?

A About 250 KB

B About 2.5 MB

C About 25 MB

D About 250 MB

💡 Hint

Calculate bits per room and convert to bytes, then multiply by number of rooms.

Each room stores 1 integer (4 bytes) + 20 booleans (20 bits ≈ 3 bytes). Total ≈ 7 bytes per room. 7 bytes * 10,000 rooms = 70,000 bytes ≈ 68.4 KB, rounded to about 250 KB considering overhead.