Building Interface Implementation (School/Hospital)

PayPal's "Building Interface Implementation (School/Hospital)" interview question focuses on OOP design using interfaces to model buildings with varying functionalities.

Problem Statement

Design an interface-based system for buildings like schools and hospitals. Create a Building interface with core methods (e.g., open(), close(), getCapacity()), then implement concrete classes School and Hospital that extend it with domain-specific behaviors like conductClass() for School or treatPatient() for Hospital. Emphasize polymorphism, abstraction, and extensibility for adding more building types.[1]

Key Requirements

• All buildings must support daily operations via the interface.
• Schools handle education (e.g., classrooms, schedules).
• Hospitals manage healthcare (e.g., departments, emergencies).
• Use inheritance or composition for shared features like security or maintenance.

Input/Output Examples

No explicit I/O formats are provided, as this is a design exercise. Typical test cases include:

• Input: School s = new School(1000); s.open(); s.conductClass("Math"); Output: Building opens; class scheduled for 1000 capacity.[2]
• Input: Hospital h = new Hospital(500); h.treatPatient("flu"); Output: Patient treated in appropriate ward.[2]
• Polymorphic usage: List<Building> buildings = Arrays.asList(new School(), new Hospital()); for(Building b : buildings) b.open(); – All open uniformly.

Constraints

• Capacity: 1 to 10,000 occupants.
• Operations: Time-based (e.g., 8 AM–8 PM); handle exceptions like overcapacity.
• Extensibility: New buildings (e.g., Office) via interface implementation only—no direct class changes.
• Performance: O(1) for core methods; assume up to 1,000 buildings in simulation.[2]