Low-Level Design for MAANG Interviews

A book-shaped table of contents for LLD interview prep: OOP fundamentals through SOLID, design principles, UML, design patterns, dependency management, reliability, concurrency, domain modeling, API design, testing, refactoring, classic interview problems, advanced architecture, and performance — cross-linking Object-Oriented Programming and Patterns instead of duplicating them.

2 — Coding Problems

Drills Design Parking Lot, Design Library System, Design Hotel Booking, Design Elevator, Design ATM, Design Chess, Design Tic Tac Toe, and Design Notification System as classic OOD interview prompts.

Object-Oriented Programming for MAANG Interviews

A book-shaped table of contents for OOP: paradigm foundations, the four pillars, object relationships, SOLID/GRASP design principles, memory and runtime internals, GoF design patterns, language-specific OOP, and OOP at system scale — cross-linking existing pattern, concurrency, and low-level-design notes instead of duplicating them.

1 — Parking Lot

Models a multi-level parking lot with heterogeneous vehicle and spot types, exercising strategy-based spot allocation and a clean split between lot, floor, and spot entities.

10 — ATM

Models an ATM's cash withdrawal, deposit, and balance-inquiry flows, exercising the state pattern across card-inserted, PIN-entry, and transaction states plus the greedy cash-dispensing algorithm.

11 — Vending Machine

Models a vending machine's product inventory, coin/payment handling, and dispensing logic, exercising the state pattern across idle, selection, payment, and dispense states.

12 — Coffee Machine

Models a coffee machine with multiple beverage recipes and shared ingredient inventories, exercising the recipe/ingredient composition model and low-stock/refill handling.