Low Level Design (LLD) Interview Questions

18 questions

Machines & State Systems

Design a Parking Lot
Easy
An interview sized parking lot with spot assignment, tickets and exit fees, explained simply in Java and Kotlin.
Design a Lift System
Medium
A small lift scheduler for interviews, with floor requests, direction and a simple step simulation in Java and Kotlin.
Design an ATM
Medium
A small ATM interview solution focused on authentication, withdrawal and known failure recovery in Java and Kotlin.
Design a Vending Machine
Easy
A simple interview vending machine with selection, payment, purchase and cancellation in Java and Kotlin.

Design Snake and Ladder
Easy
A small Snake and Ladder interview implementation with turns, jumps and exact finish rules in Java and Kotlin.
Design Tic Tac Toe
Easy
An interview sized Tic Tac Toe game with simple win checks, turn validation and draw detection in Java and Kotlin.
Design Ludo
Medium
A compact Ludo interview model with token positions, legal moves, capture and exact home rules in Java and Kotlin.
Design a Chess Game
Medium
A focused chess interview solution explaining movement, king safety and game status with Java and Kotlin code.

Design a Movie Ticket Booking System
Medium
A compact cinema booking interview solution with seat holds, expiry, confirmation and cancellation in Java and Kotlin.
Design a Food Ordering and Delivery Service
Hard
An interview sized food order with checkout validation, a fixed total and valid status changes in Java and Kotlin.
Design Booking.com
Hard
A simple hotel booking interview solution that reserves every night together and prevents overbooking in Java and Kotlin.
Design Uber
Hard
A simple ride matching interview solution with driver assignment and trip states in Java and Kotlin.
Design Splitwise
Medium
A small Splitwise interview solution for equal expenses, balances and settlement using integer money amounts.

Build a small version of a familiar Android component. Start with its main behavior, explain who owns its state, and add extra features when asked.

Implement your own LiveData
Medium
Build a small LiveData for an interview, with lifecycle aware observers, latest value delivery and short Java and Kotlin implementations.
Implement your own ViewModel
Medium
A small ViewModel store for interviews, with instance reuse, rotation ownership and cleanup in Java and Kotlin.
Implement an Event Bus
Easy
A small event bus for interviews, with subscribe, publish and unsubscribe in Java and Kotlin.
Implement a Dependency Injection Container
Medium
An interview sized dependency injection container with factories, shared instances and cycle detection in Java and Kotlin.

Design a Rate Limiter
Medium
Explain and implement one token bucket rate limiter for an interview, with a worked example and compact Java and Kotlin code.