Repository: ashishps1/awesome-low-level-design
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README.md
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This repository contains resources to learn Low Level Design (LLD) / Object Oriented Design (OOD) and prepare for interviews. It covers OOP fundamentals, design patterns, UML, concurrency and commonly asked interview questions.
👉 For a better and more comprehensive experience, checkout the LLD page at AlgoMaster.io
🧱 OOP Fundamentals
- Classes and Objects
- Enums
- Interfaces
- Encapsulation
- Abstraction
- Inheritance
- Polymorphism
🔗 Class Relationships
- Association
- Aggregation
- Composition
- Dependency
🧭 Design Principles
- DRY Principle
- YAGNI Principle
- KISS Principle
- SOLID Principles with Pictures
- SOLID Principles with Code
🧩 Design Patterns
| Creational Patterns | Structural Patterns | Behavioral Patterns |
| ----------------------------------------------------------------------------- | --------------------------------------------------------------- | ------------------------------------------------------------------------------------- |
| Singleton | Adapter | Iterator |
| Factory Method | Bridge | Observer |
| Abstract Factory | Composite | Strategy |
| Builder | Decorator | Command |
| Prototype | Facade | State |
| | Flyweight | Template Method |
| | Proxy | Visitor |
| | | Mediator |
| | | Memento |
| | | Chain of Responsibility |
🗂️ UML
- Class Diagram
- Use Case Diagram
- Sequence Diagram
- Activity Diagram
- State Machine Diagram
⏱️ Concurrency and Multi-threading Concepts
Concurrency 101
- Introduction to Concurrency
- Concurrency vs Parallelism
- Processes vs Threads
- Thread Lifecycle and States
- Race Conditions and Critical Sections
Synchronization Primitives
- Mutex (Mutual Exclusion)
- Semaphores
- Condition Variables
- Coarse-grained vs Fine-grained Locking
- Reentrant Locks
- Try-Lock and Timed Locking
- Compare-and-Swap (CAS)
Concurrency Challenges
- Deadlock
- Livelock
Concurrency Patterns
- Signaling Pattern
- Thread Pool Pattern
- Producer-Consumer Pattern
- Reader-Writer Pattern
✅ How to Answer a LLD Interview Problem
<img src="images/interview-template.png" width="350" height="250">
💻 Low Level Design Interview Problems
Easy Problems
- Design Parking Lot
- Design Stack Overflow
- Design a Vending Machine
- Design Logging Framework
- Design Traffic Signal Control System
- Design Coffee Vending Machine
- Design a Task Management System
Medium Problems
- Design ATM
- Design LinkedIn
- Design LRU Cache
- Design Tic Tac Toe Game
- Design Pub Sub System
- Design an Elevator System
- Design Car Rental System
- Design an Online Auction System
- Design Hotel Management System
- Design a Digital Wallet Service
- Design Airline Management System
- Design a Library Management System
- Design a Social Network like Facebook
- Design Restaurant Management System
- Design a Concert Ticket Booking System
Hard Problems
- Design CricInfo
- Design Splitwise
- Design Chess Game
- Design a Snake and Ladder game
- Design Ride-Sharing Service like Uber
- Design Course Registration System
- Design Movie Ticket Booking System
- Design Online Shopping System like Amazon
- Design Online Stock Brokerage System
- Design Music Streaming Service like Spotify
- Design Online Food Delivery Service like Swiggy
⏱️ Concurrency and Multi-threading Problems
- Print FooBar Alternately
- Print Zero Even Odd
- Fizz Buzz Multithreaded
- Building H2O Molecule
- Design Thread-Safe Cache with TTL
- Design Concurrent HashMap
- Design Thread-Safe Blocking Queue
- Design Concurrent Bloom Filter
- Multi-threaded Merge Sort
📇 Courses
- Master LLD Interviews - AlgoMaster.io
- Master Concurrency Interviews - AlgoMaster.io
📚 Books
- Head First Design Patterns
- Clean Code
- Refactoring: Improving the Design of Existing Code
📩 Newsletter
- AlgoMaster Newsletter
Additional resources
- Coursera - Object-Oriented Design
- Coursera - Design Patterns
- Github - Awesome Design Patterns
🤝 Contributing
Contributions are welcome! If you'd like to add a new problem, improve existing content, or fix errors:
1. Fork the repository
2. Create a feature branch:
git checkout -b feature/your-feature-name3. Commit your changes:
git commit -m 'Add some feature'4. Push to the branch:
git push origin feature/your-feature-name5. Submit a pull request
Please make sure to update Readme files and documentation as appropriate.
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