Low-Level Design (LLD) Learning Roadmap

This document outlines a my progress in learning LLD with typescript.

Project Checklists

✅ Project 1: Tic-Tac-Toe

• Implement basic game board and player mechanics
• Apply Strategy pattern for winning condition checks
• Use Factory Method for cell creation
• Follow SOLID principles throughout implementation

✅ Project 2: Snake & Ladder Game

• Core Game Mechanics

  • Board representation with snakes and ladders
  • Dice rolling mechanism
  • Player movement logic
  • Win condition detection

• Design Patterns to Implement

  • Factory Pattern: For creating tiles and obstacles
  • Strategy Pattern: For dice rolling implementation
  • Command Pattern: All game actions are encapsulated as commands
  • Event-Driven Programming: Game components communicate via events

• Technical Skills

  • Random number generation
  • Event Based Programming

✅ Project 3: Parking Lot System

• Core Functionality

  • Multiple parking spot types (compact, large, handicapped, etc.)
  • Vehicle type hierarchy
  • Ticket generation and payment processing
  • Vacancy tracking and allocation

• Design Patterns to Implement

  • Strategy Pattern: For different pricing strategies
  • Factory Method: For creating various vehicle and spot types
  • Singleton Pattern: For managing system-wide components
  • Abstract Factory Pattern: For creating families of related objects
  • Observer Pattern: For updating displays when parking availability changes
  • Command Pattern: For encapsulating operations

• Technical Skills

  • Resource allocation algorithms
  • Time-based calculations
  • Optimization techniques
  • Domain modeling
  • Building extensible software systems

✅ Project 4: Movie Ticket Booking System

• Core Functionality

  • Movie, show time, and theater management
  • Seat selection and reservation
  • Payment processing
  • Booking confirmation

• Design Patterns to Implement

  • Facade Pattern: For simplifying the booking interface
  • Proxy Pattern: For access control to booking operations
  • Memento Pattern: For saving booking state during process
  • Builder Pattern: For complex booking construction
  • Chain of Responsibility: For payment processing

• Technical Skills

  • Concurrency control
  • Transaction management
  • Timeout handling
  • Locking mechanisms

Project 5: Library Management System

• Core Functionality

  • Book and member management
  • Check-out and return processing
  • Reservation system
  • Fine calculation
  • Search functionality

• Design Patterns to Implement

  • Decorator Pattern: For adding behaviors to books (e.g., reference only)
  • Composite Pattern: For handling books and book collections
  • Iterator Pattern: For traversing catalog
  • Template Method: For standardizing book processing
  • Visitor Pattern: For operations on different library items

• Technical Skills

  • Search algorithms
  • Date-based calculations
  • Inventory tracking
  • Notification systems

Project 6: Elevator System

• Core Functionality

  • Multiple elevator coordination
  • Floor request handling
  • Efficient dispatching algorithm
  • Emergency protocols
  • Weight limits and overload handling

• Design Patterns to Implement

  • State Pattern: For elevator operational states
  • Command Pattern: For floor requests
  • Mediator Pattern: For coordinating multiple elevators
  • Observer Pattern: For floor displays and notifications
  • Strategy Pattern: For different scheduling algorithms

• Technical Skills

  • Real-time systems design
  • Optimization algorithms
  • Priority queuing
  • Fault tolerance

Project 7: Chess Game

• Core Functionality

  • Board representation
  • Piece movement rules
  • Check/checkmate detection
  • Special moves (castling, en passant, promotion)
  • Game history and notation

• Design Patterns to Implement

  • Flyweight Pattern: For efficient piece representation
  • Memento Pattern: For game state history
  • Strategy Pattern: For AI opponents
  • Command Pattern: For moves with undo capability
  • Interpreter Pattern: For parsing chess notation
  • Visitor Pattern: For piece movement validation

• Technical Skills

  • Complex rule implementation
  • Game tree algorithms
  • Minimax algorithm (for AI)
  • Algebraic notation parsing

Project 8: E-commerce Platform

• Core Functionality

  • Product catalog with categories
  • Shopping cart and checkout
  • User accounts and authentication
  • Order processing and tracking
  • Payment gateway integration
  • Inventory management

• Design Patterns to Implement

  • Microservices Pattern: For modular system architecture
  • Repository Pattern: For data access
  • CQRS Pattern: For separating read and write operations
  • Saga Pattern: For distributed transactions
  • Event Sourcing: For order tracking
  • Circuit Breaker: For handling service failures
  • Adapter Pattern: For payment gateway integration

• Technical Skills

  • Distributed systems design
  • High concurrency handling
  • System integration
  • Scalability considerations
  • Security implementation

Design Patterns Summary

Creational Patterns

• Singleton: Game engines, configuration managers
• Factory Method: Creating game pieces, UI elements
• Abstract Factory: Themed UI components, game element families
• Builder: Complex object construction (orders, bookings)
• Prototype: Cloning game states, templates

Structural Patterns

• Adapter: Integrating payment gateways, external APIs
• Bridge: Separating abstraction from implementation
• Composite: File systems, organizational hierarchies
• Decorator: Adding behaviors to base components
• Facade: Simplifying complex subsystems
• Flyweight: Efficient handling of large numbers of similar objects
• Proxy: Access control, lazy loading

Behavioral Patterns

• Chain of Responsibility: Request processing pipelines
• Command: Action encapsulation with undo capability
• Interpreter: Domain-specific languages, parsers
• Iterator: Collection traversal
• Mediator: Component coordination
• Memento: State capture and restoration
• Observer: Event handling, notifications
• State: Object behavior based on internal state
• Strategy: Interchangeable algorithms
• Template Method: Defining skeleton algorithms
• Visitor: Operations on object structures

Architectural Patterns

• MVC/MVVM: UI applications
• Microservices: Distributed systems
• Repository: Data access abstraction
• CQRS: Separating read and write operations
• Event Sourcing: Audit logging, history tracking

Learning Resources

Books

• "Design Patterns: Elements of Reusable Object-Oriented Software" by GoF
• "Head First Design Patterns" by Freeman & Robson
• "Clean Code" by Robert C. Martin
• "Refactoring" by Martin Fowler

Online Resources

• Refactoring Guru: https://refactoring.guru/design-patterns
• Source Making: https://sourcemaking.com/design_patterns

Final Projects Showcase

• Tic-Tac-Toe
• Snake & Ladder
• Parking Lot
• Movie Ticket Booking
• Library Management
• Elevator System
• Chess Game
• E-commerce Platform