Program to design parking system in Python

Suppose you want to design a parking system. A parking lot has three different kinds of parking spaces − big, medium, and small. Each size has a fixed number of available slots. We'll create a class called ParkingSystem with two methods ?

• constructor(big, medium, small) − Takes the number of slots available for different spaces and initializes the ParkingSystem object.

• addCar(carType) − Checks whether there is a parking space of the given carType for the car that wants to park.

The three slot types big, medium, and small are represented by 1, 2, and 3 respectively. A car can only park if there's an available space matching its type. If no space is available, return False, otherwise park the car and return True.

Example Scenario

If there are 2 spaces for big cars, 0 spaces for medium cars, and 1 space for small cars, the constructor call would be ParkingSystem(2, 0, 1). Here's how the addCar calls would work ?

• addCar(3) − Add one small car, returns True

• addCar(2) − No space for medium car, returns False

• addCar(3) − No more small car spaces, returns False

• addCar(1) − Add one big car, returns True

• addCar(1) − Add another big car, returns True

• addCar(1) − No more big car spaces, returns False

Implementation

Here's the complete implementation of the parking system ?

class ParkingSystem:
    def __init__(self, big, medium, small):
        # Index 0 is unused, 1=big, 2=medium, 3=small
        self.spaces = [0, big, medium, small]
    
    def addCar(self, carType):
        if self.spaces[carType] > 0:
            self.spaces[carType] -= 1
            return True
        return False

# Test the parking system
parking = ParkingSystem(2, 0, 1)

print("Adding small car:", parking.addCar(3))
print("Adding medium car:", parking.addCar(2))  
print("Adding small car again:", parking.addCar(3))
print("Adding big car:", parking.addCar(1))
print("Adding another big car:", parking.addCar(1))
print("Adding third big car:", parking.addCar(1))

Adding small car: True
Adding medium car: False
Adding small car again: False
Adding big car: True
Adding another big car: True
Adding third big car: False

How It Works

The solution uses a simple array to track available spaces. The spaces array has 4 elements where index 0 is unused, and indices 1, 2, 3 correspond to big, medium, and small car spaces respectively. When a car is added successfully, we decrement the available count for that car type.

Alternative Implementation

You can also use a dictionary for better readability ?

class ParkingSystemDict:
    def __init__(self, big, medium, small):
        self.spaces = {1: big, 2: medium, 3: small}
    
    def addCar(self, carType):
        if self.spaces[carType] > 0:
            self.spaces[carType] -= 1
            return True
        return False

# Test dictionary version
parking_dict = ParkingSystemDict(1, 1, 1)
print("Big car:", parking_dict.addCar(1))
print("Medium car:", parking_dict.addCar(2))
print("Small car:", parking_dict.addCar(3))
print("Another big car:", parking_dict.addCar(1))

Big car: True
Medium car: True
Small car: True
Another big car: False

Conclusion

The parking system efficiently manages different car sizes using a simple array or dictionary to track available spaces. The solution has O(1) time complexity for adding cars and uses minimal space to store the parking state.