LLD Problems

An N x N board game with pluggable players and constant-time win detection.

A multiplayer board game with configurable board, dice, and jump rules.

A fixed-capacity cache with O(1) get/put and least-recently-used eviction.

A logger with levels, formatters, and multiple pluggable output sinks.

Members borrow, return, and reserve book copies with due dates and fines.

A multi-floor lot that allocates spots by vehicle type and charges on exit.

A coin-and-note machine modelled as an explicit state machine.

A per-client limiter with swappable algorithms and thread-safe counters.

Card authentication, withdrawals with note dispensing, and bank integration.

Track shared expenses with equal, exact, and percentage splits and settle balances.

Send templated notifications over email, SMS, and push with preferences and retries.

Book rooms for time slots without conflicts and suggest available rooms.

Reserve stock, place orders, and handle payment and cancellation without overselling.

Search and book hotel rooms across date ranges without double-booking.

A bank of elevators that dispatches requests efficiently with pluggable scheduling.

Browse shows, hold seats temporarily, and confirm bookings under heavy contention.

Match riders with nearby drivers, track trips through their lifecycle, and price them.

Restaurants, carts, orders, and delivery-agent assignment with live status updates.

A two-player chess engine with per-piece move rules, check detection, and undo.

An in-memory broker with topics, consumer groups, offsets, and at-least-once delivery.