Design Parking System
Design a parking system for a parking lot. The parking lot has three types of parking spaces: big, medium, and small, with a fixed number of slots for each size. The system should support two operations: park and leave. The park operation checks if there is an available parking space that fits the vehicle and parks it if possible. The leave operation removes a vehicle from the parking lot.
Constraints:
- The number of parking spaces for each size is fixed and known in advance.
- Each vehicle can only be parked in a space that fits its size.
- The park operation should return false if no suitable space is available.
Examples:
Input: park(1, 1) - park a vehicle of size 1 in the parking lot with 1 big, 1 medium, and 1 small space
Output: true
Explanation: The vehicle can be parked in the big space.
Solutions
Hash Map
We use a hash map to store the number of available parking spaces for each size. The park operation checks if there is an available space that fits the vehicle and parks it if possible. The leave operation removes a vehicle from the parking lot by incrementing the count of available spaces for the corresponding size.
public
class ParkingSystem {
private int[] parkingLot;
public ParkingSystem(int big, int medium, int small) {
parkingLot = new int[] {
big, medium, small}
;
}
public boolean park(int carType, int carId) {
if (parkingLot[carType - 1] > 0) {
parkingLot[carType - 1]--;
return true;
}
return false;
}
public void leave(int carType, int carId) {
parkingLot[carType - 1]++;
}
}Follow-up:
How would you modify the design to support multiple parking lots?
