How are we checking if a vehicle can fit or not?

[praveenksgv]

awesome-low-level-design/solutions/java/src/parkinglot/entities/ParkingSpot.java

Line 50 in 43017e5

return spotSize == VehicleSize.SMALL;

Shouldn't it be:
return spotSize = VehicleSize.SMALL || spotSize == VehicleSize.MEDIUM || spotSize == VehicleSize.LARGE;

[Chiraggupta0]

@praveenksgv Thanks for the question!
In this implementation, the intention is to follow strict size matching — meaning a SMALL vehicle should only occupy a SMALL spot. This prevents smaller vehicles from blocking MEDIUM or LARGE spots unnecessarily.

If we allow:

spotSize == SMALL || spotSize == MEDIUM || spotSize == LARGE

then every spot would become valid for a SMALL vehicle, which breaks the size-based allocation strategy.

So the current logic is correct based on the chosen design.
If we decide to support flexible fitting in the future (small vehicle can take larger spots), we can update the logic across the system accordingly.

[praveenksgv]

@Chiraggupta0 Thanks Chirag. Then why are we using return spotSize == VehicleSize.MEDIUM || spotSize == VehicleSize.LARGE; in next statement, shouldn't it be just return spotSize == VehicleSize.MEDIUM
https://github.com/ashishps1/awesome-low-level-design/blob/43017e5e22eeedcf74234e6b80fcbec3a7554ab5/solutions/java/src/parkinglot/entities/ParkingSpot.java#L52C17-L52C77

[Chiraggupta0]

@praveenksgv You're correct ( Based on the code Small Switch case should return vehicle size of small , medium , and large)
However, the reason we don’t allow SMALL vehicles to fit into all spot sizes is because the system uses ASYMMETRIC SIZE RULES BY DESIGN :
SMALL → only SMALL (strict matching)
MEDIUM → MEDIUM or LARGE (flexible upward)
LARGE → only LARGE
This avoids SMALL vehicles from taking up MEDIUM or LARGE spots and blocking vehicles that actually need those sizes.
So even though MEDIUM vehicles have upward flexibility, SMALL vehicles intentionally do not , to keep the parking allocation efficient.

[praveenksgv]

Thanks @Chiraggupta0

I just wanted to understand the logic here. It wasn't consistent and that confused me. Is it fine if I add a comment here mentioning this? Want it to be clear so that others has to spend less time understanding it.

[Chiraggupta0]

Thanks @praveenksgv
Yes, that would be perfectly fine.
If the logic wasn’t immediately intuitive, adding a concise comment to clarify the design intent will certainly help future readers and contributors.