This repository is a learning playground for developers to practice solving real-world software problems using Design Patterns and SOLID Principles.
Instead of just reading theory, you will tackle practical coding challenges that simulate real engineering problems. Each challenge requires you to:
- Implement a solution in any programming language.
- Apply appropriate design patterns.
- Follow SOLID principles.
- Explain why you chose your approach, including trade-offs and alternatives.
The goal is not only to write working code but to think like a software architect.
Modern software development is not just about “making it work” — it’s about building scalable, maintainable, and extensible systems.
This repo exists to help developers:
- Understand when and why to use design patterns (not just how).
- Practice SOLID principles in real scenarios.
- Learn trade-offs of different design decisions.
- Improve communication skills by explaining solutions clearly.
- Think beyond syntax and develop architectural thinking.
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Each problem is defined in a structured format with:
- Problem Statement
- Requirements
- Deliverables
- Evaluation Criteria
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Developers solve the problem using any language.
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Developers submit:
- Their code implementation.
- A short write-up explaining:
- The design pattern(s) used.
- How SOLID principles were applied.
- Trade-offs in the chosen solution.
- Possible alternative approaches.
By completing these challenges, you will:
- ✅ Get hands-on practice with GoF design patterns (Factory, Strategy, Observer, etc.).
- ✅ Apply SOLID principles to make code cleaner and extensible.
- ✅ Learn to reason about design trade-offs.
- ✅ Build the habit of writing maintainable, future-proof code.
- ✅ Improve your ability to explain technical choices (a key interview and leadership skill).
- Email service management (Strategy / Factory + SRP).
- Payment gateway integration (Open/Closed + Strategy).
- Notification system (Observer pattern).
- Report generation with multiple formats (Factory + OCP).
- Logger system with multiple outputs (Decorator / Strategy).
- Plugin-based architecture (Dependency Inversion + Factory).
Each challenge is mapped to one or more design patterns and SOLID principles so you get structured learning.
- Junior Developers → Learn clean design early.
- Mid-Level Developers → Strengthen architecture & pattern usage.
- Senior Engineers / Leads → Sharpen explanation and trade-off reasoning.
- Interview Preparation → Many interview questions ask about design & SOLID.
- Think beyond coding → design & architecture mindset.
- Reduce “spaghetti code” by following SOLID & patterns.
- Become more confident in interviews and technical discussions.
- Sharpen your ability to justify design decisions (trade-offs).
- Build a portfolio of design-focused problems you can showcase.
- problems.md/ → Contains all defined challenges.
- solutions/ → Developers submit their solutions and explanations.
- README.md → You are here.
- Pick any problem.
problem is defined in md file - Solve it in your preferred programming language.
- Add your solution to
/solutions/<your-name-or-team>/problem_name. - Include a README or notes explaining your thought process.
- Create the PR and after the successful review process the PR will be merged and available for other developers to take inspiration from your code.
This repository is about learning by doing.
You may not always pick the "perfect" design pattern — and that’s fine! The goal is to practice reasoning, understand trade-offs, and grow as a software designer.
💡 “Code is read more often than it is written. Design patterns and SOLID help us write code that future developers (including you) can read and extend with ease.”