LLD Problems: Parking Lot, Elevator, Chess, etc.

Chess is a board of cells with polymorphic per-piece move rules, strict turn management, and check detection.

A file system is a recursive tree where directories and files share a common node interface via the Composite pattern.

A food delivery app runs an order through a strict status state machine from placed to delivered, with payment and agent assignment.

A hotel system reserves a typed room for a guest over a date range and manages the booking lifecycle with a cancellation policy.

A library lends concrete copies of abstract titles, tracking issue, return, renewal, reservation, and fines.

A logging framework filters by level, formats the message, and fans it out to multiple appenders, safely across threads.

A movie booking system sells seats for shows with short-lived seat locks that prevent double-selling under heavy concurrency.

A vending machine is a state machine that collects money, validates stock, dispenses a product, and returns change.

An ATM is a state machine that authenticates, enforces limits, dispenses cash, and keeps the account in sync.

A shopping cart totals items, applies discounts, validates inventory at checkout, and charges payment atomically.

A parking lot assigns the nearest compatible spot, issues a ticket, and charges by duration at exit.

An elevator system dispatches hall requests to the best car and runs each car as a direction-aware state machine.