Low level design interview problems

22 topics.

• 01FoundationReadDesign a parking lotSpot assignment by size, tickets, and two cars racing for one spot.
• 02FoundationReadDesign tic-tac-toeA small game that tests clean turn handling and O(1) win checks.
• 03FoundationReadDesign a vending machineThe classic state machine: idle, has money, dispensing, out of stock.
• 04FoundationReadDesign an LRU cacheO(1) get and put with a hash map and a doubly linked list.
• 05Mid-levelReadDesign a rate limiterToken bucket vs sliding window, behind one swappable interface.
• 06FoundationReadDesign a logging frameworkLevels, appenders and formatters wired with chain of responsibility.
• 07FoundationReadDesign snake and ladderBoard modeling, pluggable dice, and extensible game rules.
• 08SeniorReadDesign an elevator systemDispatching many cars to many floors without starving anyone.
• 09FoundationReadDesign an ATMCard sessions, cash dispensing, and failure in the middle of a withdrawal.
• 10FoundationReadDesign a library management systemMembers, loans, reservations and fines without a god class.
• 11SeniorReadDesign a movie ticket booking systemSeat holds that expire, and two people clicking the same seat.
• 12Mid-levelReadDesign a hotel booking systemSelling room types per night, rooms picked at check-in, changes and cancellations.
• 13Mid-levelReadDesign SplitwiseEqual, exact and percent splits, and simplifying who owes whom.
• 14SeniorReadDesign an in-memory pub-sub systemTopics, subscribers, ordering and backpressure in one process.
• 15SeniorReadDesign a task schedulerDelayed and recurring jobs with a priority queue and worker threads.
• 16Mid-levelReadDesign an in-memory file systemFiles and folders as a composite tree with paths and permissions.
• 17Mid-levelReadDesign a text editor with undo and redoCommand pattern, history stacks, and memory limits.
• 18SeniorReadDesign chessPiece moves as strategies, game state, check and checkmate.
• 19Mid-levelReadDesign a car rental systemFleet inventory by branch, reservations, and pricing rules.
• 20SeniorReadDesign a food delivery appOrders, restaurants and delivery partners as a state machine.
• 21SeniorReadDesign a stock exchange order bookPrice-time priority matching with buy and sell books.
• 22Mid-levelReadDesign a notification serviceEmail, SMS and push behind one interface, with retries and templates.

More in Low Level Design

• Foundations
• SOLID principles
• Design patterns
• Low Level Design overview