How to read these walkthroughs
011 · Spec
In / out of scope
022 · Model
Who owns rules
033 · API
User verbs
044 · Trace
Happy + fail + race
Each deep dive matches a strong ~35-minute talk track. Use the delivery framework.
- Parking lot · complete solution — spots, tickets, cents fees, relational occupancy.
- Rate limiter · complete solution — Factory + Strategy, Token Bucket, Sliding Window Log, per-key locks.
- Elevator · complete solution — step() simulation, SCAN, hall vs destination.
Concurrency callouts
Order to practice
Treat this hub as a practice queue, not reading material. For parking / rate limiter / elevator: timer on, phone away, talk out loud.
- Day 1 — Parking lot: enter/exit + fee in cents; reject full lot. Complete solution.
- Day 2 — Rate limiter: Token Bucket allow/deny with one key; mention Sliding Log trade-off. Complete solution.
- Day 3 — Elevator: step() simulation, hall vs cabin, SCAN narrative. Complete solution.
- Day 4 — Redo the weakest one under concurrency follow-up pressure.