1603. Design Parking System

1603. Design Parking System

Tag: Design Hash Table

Difficulty: Easy

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 1, 2, 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.

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Example 1:

Input
["ParkingSystem", "addCar", "addCar", "addCar", "addCar"]
[[1, 1, 0], [1], [2], [3], [1]]
Output
[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.

Constraints:

• 0 <= big, medium, small <= 1000
• carType is 1, 2, or 3
• At most 1000 calls will be made to addCar

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Hash Table

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.memo = collections.defaultdict(int)
        self.memo[1] = big
        self.memo[2] = medium
        self.memo[3] = small

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



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

Array

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.parking_lot = [None] * (big + medium + small)
        self.big = big
        self.medium = medium
        self.small = small

    def addCar(self, carType: int) -> bool:
        if carType == 1:
            limit = self.big
        elif carType == 2:
            limit = self.medium
        else:
            limit = self.small

        count = 0
        for slot, size in enumerate(self.parking_lot):
            if size == carType:
                count += 1
            if count == limit:
                return False
            if not self.parking_lot[slot]:
                self.parking_lot[slot] = carType
                return True

        return False


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

Two Arrays & Count

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.parking_lot = [None, big, medium, small]
        self.count = [None, 0, 0, 0]

    def addCar(self, carType: int) -> bool:
        if self.count[carType] < self.parking_lot[carType]:
            self.count[carType] += 1
            return True

        return False

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

One Array

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.parking_lot = [None, big, medium, small]

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

        return False

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