[LeetCode]#1603. Design Parking System

Environment: Python 3.7

Key technique: class, _init_, self

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.

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.

Analysis:

1. Input parking space [1:1, 2:1, 3:0] means big, medium, and small parking space.
2. Input parking car size. If parking space is larger than 1, return True and subtract 1.
3. If parking space is equal to 0, return False.

Solution:

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

Submissions:

Reference:

https://leetcode.com/problems/design-parking-system/discuss/960876/Python3-Hashtable-implementation