Most Frequently Asked Low Level Design(LLD) Interview Questions
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Most Frequently Asked Low Level Design(LLD) Interview Questions
Below are the curated list of most commonly asked Low Level Design (LLD) interview problems. Each problem includes a short description and a link to the complete solution with code and class diagrams.
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Design Parking Lot System
The system should handle parking for different vehicle types such as bikes, cars, and trucks. It should manage slot allocation, availability tracking, and entry/exit flow. The design also ensures efficient usage of parking space under varying load conditions.
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Design Elevator / Lift System
The system should support multiple elevators operating across floors with request handling logic. It focuses on scheduling algorithms to minimize wait time and optimize movement. It also manages direction control and concurrent floor requests.
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Design Movie Ticket Booking System
The system should allow users to browse movies, select shows, and book seats. It handles seat locking, availability updates, and booking confirmation flow. It also ensures consistency when multiple users try to book the same seats.
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Design Snake and Ladder Game
The system should simulate a board game with dice rolls, player turns, snakes, and ladders. It manages player movement rules and game progression. It also determines winning conditions based on board state.
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Design Hotel Management System
The system should handle room inventory, booking, and check-in/check-out processes. It maintains availability across different room types and manages reservations. It also supports cancellation and booking updates.
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Design Food Delivery System
The system should manage restaurant listings, order placement, and delivery assignment. It tracks order status from placement to delivery. It also ensures correct mapping between users, restaurants, and delivery partners.
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Design Library Management System
The system should handle book inventory, issuing, returning, and user borrowing history. It ensures books are tracked properly across multiple copies and users. It also manages overdue tracking and availability.
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Design Notification System
The system should support sending notifications via email, SMS, and push channels. It handles routing messages based on user preferences and delivery rules. It also ensures retry mechanisms for failed deliveries.
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Design Real-Time Chat Application
The system should enable real-time messaging between users with low latency delivery. It manages conversations, message history, and online presence. It also supports one-to-one and group chats.
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Design Ride Sharing System
The system should match riders with nearby drivers and manage trip lifecycle. It calculates fares based on distance, demand, and availability. It also handles ride booking, cancellation, and driver allocation.
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Design E-commerce System
The system should manage product catalog, cart operations, and order checkout flow. It supports inventory tracking and payment processing. It also handles order status updates and customer history.
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Design Splitwise System
The system should handle splitting shared expenses among users and tracking balances. It simplifies debts between multiple users for easier settlement. It also maintains transaction history for transparency.
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Design File Storage System (Google Drive / Dropbox)
The system should manage file uploads, folder hierarchy, and access control. It supports sharing files between users with permissions. It also ensures scalable storage organization and retrieval.
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Design Rate Limiter
The system should control request traffic to prevent abuse of APIs or services. It enforces limits per user or system within a time window. It also ensures fair usage across multiple clients.
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Design Airline Reservation System
The system should manage flight search, seat booking, and ticket reservations. It handles seat availability and cancellation workflows. It also ensures consistency during concurrent bookings.
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Design ATM System
The system should handle cash withdrawal, balance inquiry, and secure authentication. It manages transactions between ATM machines and bank accounts. It also ensures transaction safety and failure handling.
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Design Shopping Cart System
The system should manage items added to a cart and calculate total pricing. It supports updates, removals, and checkout flow. It also ensures cart persistence for users.
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Design Social Media Platform
The system should support user posts, feeds, likes, and follow relationships. It handles content visibility and feed generation. It also manages user interactions at scale.
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Design Online Bookstore
The system should manage book listings, search, and purchase flow. It handles inventory and customer orders. It also supports order history and recommendations.
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Design Meeting Scheduler System
The system should manage meeting creation and participant scheduling. It checks availability and prevents conflicts. It also supports updates and cancellations.
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Design Order Inventory Management System
The system should manage products, sellers, and inventory stock levels. It ensures orders are placed only when sufficient stock is available. It also updates inventory after each successful order.
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Design Customer Issue Resolution System
The system should manage customer complaints and ticket assignment workflows. It tracks issue status from creation to resolution. It also ensures proper escalation handling.
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Design Chess Game
The system should simulate a chess game with board setup and piece movement rules. It manages player turns and validates legal moves. It also handles check, checkmate, and game state transitions.
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Design Text Editor / Word Processor
The system should support document creation, editing, formatting, and versioning. It also handles undo/redo operations and real-time collaborative-ready structure. It mimics basic behavior of tools like Microsoft Word.
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