Day: June 8, 2025

This roadmap is built for software engineers preparing for LLD interviews at top-tier product companies like MAANG (Meta, Amazon, Apple, Netflix, Google) and other tech giants (Uber, Flipkart, etc.). It covers all the essential topics, patterns, and subtopics with a focus on hands-on system design and coding skills. ✅ Phase 1: OOPs & Design Principles (Foundational) Learn how to write clean, extensible, and maintainable code. Object-Oriented Programming (OOP) Classes & Objects Inheritance, Polymorphism, Encapsulation, Abstraction Composition vs Inheritance Aggregation vs Association Constructor chaining SOLID Principles Single Responsibility Principle (SRP) Open/Closed Principle (OCP) Liskov Substitution Principle (LSP) Interface Segregation Principle (ISP) Dependency Inversion Principle (DIP) Other Core Principles DRY (Don’t Repeat Yourself) YAGNI (You Aren’t Gonna Need It) KISS (Keep It Simple, Stupid) Law of Demeter ✅ Phase 2: Design Patterns (Classic & GoF) Understand and apply reusable design patterns in interviews and real-world projects. Creational Patterns Singleton (Thread-safe, Lazy/Eager Initialization) Factory Method Abstract Factory Builder Prototype Structural Patterns Adapter Decorator Proxy (Static & Dynamic) Facade Composite Flyweight Behavioral Patterns Strategy Observer Command State Template Method Chain of Responsibility Mediator Iterator Memento ✅ Phase 3: Hands-on Design Practice (Object Modeling) Learn how to model real-world problems in code using OOPs + Design Patterns. Must-Practice Real-World LLD Problems Design a Parking Lot Design an Elevator System Design a Tic-Tac-Toe / Chess Game Design a Movie Ticket Booking System Design a Cab Booking System (Uber) Design a Hotel Management System Design an ATM Design a Library Management System Design a Splitwise App Design a File System (Folder Structure) Design Snake and Ladder / Ludo Design Notification System (Email/SMS/Push) What to Practice in Each Design: Identify core entities and relationships Apply correct design principles (SRP, OCP) Choose and apply right design patterns Handle concurrency & multithreading where required Discuss scalability and extensibility Interface vs abstract class usage ✅ Phase 4: Advanced Concepts for MAANG Deep dive into architecture and scalable components to impress interviewers. Concurrency & Multithreading Thread-safe Singleton Producer-Consumer BlockingQueue, ThreadPool Locks, Semaphores Event-driven architecture (Observer) Best Practices UML Diagrams (Class, Sequence, Activity) Testability of components Handling large data sets in memory (pagination, caching) Extensible plugin-based architecture Principles to Keep in Mind Favor composition over inheritance Program to interface, not implementation Interface segregation Fail fast and recover gracefully 🛠️ Tools & Practice Platforms UML Tools: Lucidchart, draw.io, Creately Practice: InterviewBit, DesignGurus, LowLevelDesign.io, GitHub repos Mock Interviews: Pramp, Exponent, peers 🧪 How to Practice LLD Interviews Choose a design problem Draw class diagram (entity modeling) Write class skeletons with methods Identify design patterns if applicable Add validations, edge cases Discuss improvements, scalability 🎯 Final Advice for MAANG LLD Success Always start with requirements & assumptions Focus on extensibility, not overengineering Communicate while designing; it’s a discussion Think in layers: controller → service → model → data Read open-source Spring projects or Java repositories to see real-world architecture 💡 Consistency in practicing 1–2 LLD problems per week for 2–3 months will significantly improve your chances of cracking MAANG-level design rounds.

Day: June 8, 2025

🧠 Low-Level Design (LLD) Roadmap for MAANG Interviews (2025)

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