Go deep (with complete solutions)
- BookMyShow · complete solution — City→Cinema→Show, AVAILABLE→LOCKED→BOOKED, payment stub.
- Movie ticket booking · complete solution — search/browse, showtime seat state, holds as extension.
- Inventory management · complete solution — multi-warehouse stock, atomic transfers, Observer low-stock.
- Amazon Locker · complete solution — deposit/pickup, tokens, staff reclaim.
- Book library · complete solution — Book vs BookItem, checkout/return, fines, reservation queue.
Concurrency callouts
Order to practice
Treat this hub as a practice queue, not reading material. For booking / inventory / locker / library: timer on, phone away, talk out loud.
- Day 1 — Drill the shared skeleton: FREE → HELD(TTL) → COMMITTED / RELEASED on a whiteboard.
- Day 2 — Movie booking then BookMyShow: two concurrent bookers. BMS solution · movie solution.
- Day 3 — Inventory transfer across warehouses. Complete solution.
- Day 4 — Locker deposit + pickup + reclaim. Complete solution.
- Day 5 — Library: Book vs BookItem + reservation queue. Complete solution.