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CS ConceptsLLD

LLD

Low-level design walkthroughs: parking lots, elevators, rate limiters.

12 notes · 47 min total

  1. 1How to Approach an LLD InterviewA step-by-step framework for low-level design interviews: requirements, entities, class design, implementation and extensions.6 min
  2. 2LLD Practice ProblemsA graded list of classic low-level design problems, from warm-ups to concurrency-heavy systems, with links to worked designs.1 min
  3. 3Vending MachineDesign a vending machine as a small state machine with inventory, incremental payment, change, cancel and restock.4 min
  4. 4Connect FourDesign Connect Four: a 6x7 board, gravity drops, turn switching, and O(1)-per-move win detection along four axes.4 min
  5. 5Logging ServiceDesign a logger with level filtering and pluggable formatters and destinations, using the Strategy pattern.3 min
  6. 6Parking LotDesign a single-level parking lot with size-matched slots, tickets, O(1) slot assignment and a pluggable pricing strategy.4 min
  7. 7Elevator SystemDesign a single elevator that serves requests with the SCAN algorithm using a min-heap for up and a max-heap for down.4 min
  8. 8Package Locker SystemDesign self-service package lockers: best-fit locker assignment by size, one-time pickup codes, and freeing lockers on pickup.4 min
  9. 9In-Memory File SystemDesign an in-memory file system as a tree of nodes with create, read, write, ls and delete on Unix-style paths.4 min
  10. 10Inventory ManagementDesign a single-warehouse inventory that adds products, adjusts stock without going negative, and raises low-stock alerts.4 min
  11. 11Rate LimiterDesign a per-user sliding-window-log rate limiter with retry-after hints, lazy eviction and per-user locking.4 min
  12. 12Movie Ticket Booking SystemDesign movie seat booking with per-show seat state, all-or-nothing seat locking, payment, and per-show thread safety.5 min