LeetCode 1603. Design Parking System



Design a parking system for a parking lot. The parking lot has three kinds of parking spaces: big, medium, and small, with a fixed number of slots for each size.

Implement the ParkingSystem class:

  • ParkingSystem(int big, int medium, int small) Initializes object of the ParkingSystem class. The number of slots for each parking space are given as part of the constructor.
  • bool addCar(int carType) Checks whether there is a parking space of carType for the car that wants to get into the parking lot. carType can be of three kinds: big, medium, or small, which are represented by 12, and 3 respectively. A car can only park in a parking space of its carType. If there is no space available, return false, else park the car in that size space and return true.

Example 1:

["ParkingSystem", "addCar", "addCar", "addCar", "addCar"]
[[1, 1, 0], [1], [2], [3], [1]]

[null, true, true, false, false]

Explanation ParkingSystem parkingSystem = new ParkingSystem(1, 1, 0); parkingSystem.addCar(1); // return true because there is 1 available slot for a big car parkingSystem.addCar(2); // return true because there is 1 available slot for a medium car parkingSystem.addCar(3); // return false because there is no available slot for a small car parkingSystem.addCar(1); // return false because there is no available slot for a big car. It is already occupied.


  • 0 <= big, medium, small <= 1000
  • carType is 12, or 3
  • At most 1000 calls will be made to addCar


Create a dictionary for slot tracking.

Python Solution

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.slot = {
            1: big,
            2: medium,
            3: small

    def addCar(self, carType: int) -> bool:
        if self.slot[carType] == 0:
            return False
        self.slot[carType] = self.slot[carType] - 1
        return True

# Your ParkingSystem object will be instantiated and called as such:
# obj = ParkingSystem(big, medium, small)
# param_1 = obj.addCar(carType)
  • Time Complexity: O(1)
  • Space Complexity: O(1)

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