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Early-stage Startup·Software Engineer·Take-home Assignment·Intermediate

IntermediatePending
Jun 2026

Summary

Final round for a SWE role, got a take-home to build a Car Rental System using OOP in 2-4 hours, then a 60-90 minute interview with two engineers to walk through the solution. Mostly anxious about whether they'd ask me to code live on top of it.

Questions Asked (1)

Q1

Design and implement a Car Rental System using OOP principles in a language of your choice, within a 2-4 hour window.

System DesignTechnical Trade-offsData Modeling
Author's notes

The time box stressed me out more than the problem itself.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scope with the interviewer, then sketch a high-level class diagram focusing on core entities and their relationships. Implement a minimal working version with clean, extensible code, and be prepared to discuss trade-offs and potential enhancements.

Pro tip: Prioritize a working, well-structured core over feature completeness; demonstrate how your design can easily accommodate new requirements like pricing strategies or vehicle types.

1. Clarify Requirements and Scope

Ask questions to understand must-have features (e.g., vehicle types, rental periods, pricing) and constraints (time, language). Define a minimal viable product scope.

2. Design Core Classes and Relationships

Identify main entities (Vehicle, Customer, Rental, etc.) and their attributes, methods, and associations. Use UML or simple sketches to visualize.

3. Implement Core Functionality

Code the essential classes and methods, focusing on clean code, separation of concerns, and extensibility. Use design patterns where appropriate.

4. Test and Validate

Write basic unit tests or a simple driver to demonstrate the system works for key scenarios (e.g., renting, returning, calculating fees).

5. Discuss Trade-offs and Extensions

Explain design decisions, trade-offs (e.g., simplicity vs. flexibility), and how you would extend the system for scalability or new features.

Key Points to Mention

  • Encapsulation and abstraction: hiding internal details and exposing clear interfaces.
  • Inheritance and polymorphism: using base classes (e.g., Vehicle) and subclasses (Car, Truck) for extensibility.
  • Design patterns: Strategy for pricing, Factory for vehicle creation, Singleton for rental system manager.
  • SOLID principles: ensuring single responsibility, open/closed, etc.
  • Data modeling: relationships between entities (e.g., Customer has many Rentals, Rental has one Vehicle).
  • Trade-offs: balancing time constraints with code quality, and choosing simplicity over over-engineering.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.