Design Parking System
A easy-tier problem at 87% community acceptance, tagged with Design, Simulation, Counting. Reported in interviews at Valve and 1 others.
Design Parking System is asked at Valve and Amazon, but it's easy enough that most candidates expect a walk. The 87% pass rate hides a trap: people overthink it or miss the state management part during screen share. You're building a data structure that tracks available spots across multiple parking tiers. The actual code is simple, but under pressure you might lose track of which tier maps to which count, or forget to decrement correctly. If this hits your live OA and you blank on the structure, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Design Parking System"
Design Parking System is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe trick isn't algorithmic, it's design clarity. You need a way to track how many free spots exist in each tier (big, medium, small, compact) and allow parking and unparking operations. The obvious trap: not initializing your counts properly or using the wrong data type. Most candidates go for a simple array or hash map keyed by spot size, then increment and decrement as cars come and go. The real skill is handling edge cases like trying to park when no spots exist. Under time pressure during a live assessment, candidates often implement the core logic fast but forget to validate whether a spot is actually available before returning a spot number. That's where StealthCoder steps in, surfacing a validated solution if you hit the wall.
Pattern tags
You know the problem.
Make sure you actually pass it.
Design Parking System recycles across companies for a reason. It's easy-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Design Parking System interview FAQ
Is Design Parking System still asked at Amazon interviews?+
Yes. It appears in the input data as an Amazon question. It's a system design warm-up, often paired with follow-ups about scaling or concurrency. The 87% pass rate means most who see it pass, but that's because it's easy, not because it's not asked anymore.
What's the actual trick to this problem?+
There isn't a deep algorithmic trick. You track available counts per tier and validate before returning a spot. The 'trick' is state management: decrement on park, increment on unpark, check availability before assignment. Clean code and correct logic matter more than optimization.
Do I need to use OOP for this problem?+
The problem name is 'Design Parking System,' which suggests a class-based approach. Most interviewers expect you to define a ParkingSystem class with addCar and removeCar methods. Using plain functions won't hurt your logic, but OOP is the conventional fit here.
How does Design Parking System relate to the Design topic?+
It tests whether you can model a real-world system as code: choosing the right data structure, handling state transitions, and keeping logic readable. This is foundational system design thinking, not just pattern matching.
What's the most common mistake on this problem?+
Forgetting to check if a spot is available before returning a spot number. Candidates implement park and unpark but don't guard against the case where a tier is full. That one-line check is often what separates a clean solution from a failed submission.
Want the actual problem statement? View "Design Parking System" on LeetCode →