Low-Level Design
20 object-oriented design problems frequently asked in interviews. Each includes design patterns, key classes, and a structured approach.
📐 LLD Foundations
Master SOLID principles, Design Patterns & OOP before tackling problems
Design Tic-Tac-Toe
Design a flexible Tic-Tac-Toe game supporting an N×N board with configurable win conditions.
Design Snake and Ladder Game
Design a Snake and Ladder board game supporting multiple players with configurable board, snakes, and ladders.
Design a Parking Lot System
Design the classes and interfaces for a multi-floor parking lot that supports different vehicle types.
Design a Vending Machine
Design the classes for a vending machine that dispenses products, accepts payments, and returns change.
Design an ATM Machine
Design the object model for an ATM that handles authentication, withdrawals, deposits, and balance inquiries.
Design a Library Management System
Design classes for a library that manages books, members, borrowing, reservations, and fines.
Design a Hotel Booking System
Design classes for a hotel reservation system with room management, booking, and payment processing.
Design a Car Rental System
Design classes for a car rental service with vehicle inventory, reservations, and billing.
Design a Restaurant Management System
Design classes for a restaurant system covering table reservations, ordering, kitchen workflow, and billing.
Design an Online Shopping Cart
Design classes for an e-commerce shopping cart with products, pricing rules, discounts, and checkout.
Design Splitwise / Expense Sharing
Design classes for an expense-sharing application that tracks group expenses and calculates optimal settlements.
Design Stack Overflow / Q&A Platform
Design the classes for a Q&A platform where users post questions, answers, comments, and vote on content.
Design Social Media (Simplified)
Design core classes for a simplified social media platform with users, posts, feed, friendships, and notifications.
Design an Elevator System
Design the object model for an elevator system in a high-rise building with multiple elevators.
Design a Chess Game
Design the object-oriented model for a two-player chess game with full rule enforcement.
Design Movie Ticket Booking (BookMyShow)
Design classes for an online movie ticket booking platform with seat selection, shows, and payments.
Design a File System (Linux-like)
Design the object model for a hierarchical file system with files, directories, and permissions.
Design a Logging Framework
Design a flexible, extensible logging framework similar to Log4j or SLF4J.
Design a Pub-Sub Messaging System
Design a publish-subscribe messaging system where publishers send messages to topics and subscribers receive them.
Design a Task Scheduler / Cron
Design a job scheduling system that executes tasks at specified times or intervals, similar to cron.