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lld

8 articles across 5 sub-topics

Sub-topic

Design Patterns

4 articles

LLD for Parking Lot System: Designing a Smart Garage

TLDR 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/CompactSp

Mar 9, 2026•19 min read

LLD for Elevator System: Designing a Smart Lift

TLDR TLDR: An elevator system is a textbook OOP design exercise: ElevatorCar encapsulates its stop queue, ElevatorState polymorphically handles direction changes (State Pattern), and DispatchStrategy

Mar 9, 2026•22 min read

LLD for Tic-Tac-Toe: Designing an Extensible OOP Game

TLDR: 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 Patt

Feb 20, 2026•20 min read

LLD for Ride Booking App: Designing Uber/Lyft

TLDR: 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 pricin

Feb 11, 2026•21 min read

Sub-topic

Database

1 article

LLD for URL Shortener: Designing TinyURL

TLDR 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 IDs

Mar 9, 2026•22 min read

Sub-topic

Concurrency

1 article

LLD for Movie Booking System: Designing BookMyShow

TLDR 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 u

Mar 9, 2026•25 min read

Sub-topic

Caching

1 article

LLD for LRU Cache: Designing a High-Performance Cache

TLDR 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 Li

Mar 9, 2026•25 min read

Sub-topic

Coding Interview

1 article

Implement LLD for Parking Lot: Code Walkthrough

TLDR: 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, an

Mar 9, 2026•29 min read