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Design Patterns
Learn Design Patterns as a connected topic across chapters, concepts, simulations, and interview reasoning.
Design PatternsMental ModelTradeoffsFailure ModesInterview ReasoningLLD for Parking Lot System
Begin with
LLD for Parking Lot System gives you the cleanest entry point before branching into constraints, failures, and related systems.
9
Chapters
10
Concepts
Related systems
Follow the nearby ideas
Use the map as a quiet orientation layer, then move back into the articles for depth.
Guidance
Design Patterns
Continues from what you have already explored.
System behavior
HyperLogLog Cardinality Estimation
Hash values route into registers, leading-zero runs update maxima, and the harmonic mean estimates unique cardinality with bounded error.
Step 1 / 3Normal flow
Read in sequence
1LLD for Parking Lot System: Designing a Smart GarageTLDR
TLDR: A Parking Lot is the "Hello World" of Low-Level Design. It teaches Encapsulation (ParkingFloor hides its Min-Heap), Abstraction (PricingStrategy interface), Inheritance (BikeSpot/CompactSp19 min2LLD for URL Shortener: Designing TinyURLTLDR
TLDR: A URL Shortener maps long URLs to short IDs. The core challenge is generating a globally unique, short, collision-free ID at scale. We use Base62 encoding on auto-incrementing database IDs22 min3LLD for Movie Booking System: Designing BookMyShowTLDR
TLDR: A Movie Booking System (like BookMyShow) is an inventory management problem with an expiry: seats expire when the show starts. The core engineering challenge is preventing double-booking u25 min4LLD for LRU Cache: Designing a High-Performance CacheTLDR
TLDR: An LRU (Least Recently Used) Cache evicts the item that hasn't been accessed the longest when it's full. The classic implementation combines a HashMap (O(1) lookup) with a Doubly Linked Li25 min5LLD for Elevator System: Designing a Smart LiftTLDR
TLDR: An elevator system is a textbook OOP design exercise: ElevatorCar encapsulates its stop queue, ElevatorState polymorphically handles direction changes (State Pattern), and DispatchStrategy22 min6Implement LLD for Parking Lot: Code WalkthroughTLDR: This is the code companion to the Parking Lot System Design post. We implement the core classes (ParkingLot, ParkingSpot, Ticket) in Java, apply the Singleton, Factory, and Strategy patterns, an29 min7LLD for Tic-Tac-Toe: Designing an Extensible OOP GameTLDR: Tic-Tac-Toe looks trivial — until the interviewer says "make it N×N with P players and pluggable winning rules." The key design decisions: a Board abstracted from piece identity, a Strategy Patt20 min8LLD for Ride Booking App: Designing Uber/LyftTLDR: A ride-booking system (Uber/Lyft-style) needs three interleaved sub-systems: real-time driver location tracking (Observer Pattern), nearest-driver matching (geospatial query), and dynamic pricin21 min9Strategy Design Pattern: Simplifying Software DesignTLDR: The Strategy Pattern replaces giant if-else or switch blocks with a family of interchangeable algorithm classes. Each strategy is a self-contained unit that can be swapped at runtime without tou12 min
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