Parking Lot Algorithm

This project describes and solves the parking lot problem using TypeScript and Object-Oriented Programming pattern.

The problem

Design an Object-Oriented parking lot using any programming language features.

The Solution

Model

We're going to implement a generic parking lot ticketing system, using the following classes and interfaces:

• Ticket
• Vehicle, Car
• Parking Lot

Ticket

The Ticket class is used by Vehicle class: it describes the associations between the parked Vehicle and the entering ticket. It defines an id, entry and exit Date. The id is calculated using the combination between current time and license plate of car.

```txt

---

| Ticket | |-----------------------| | + id: string | | + enterDate: DateTime |

| + exitDate: DateTime |

```

Vehicle

The Vehicle class contains some attributes about Vehicle dimensions, and brand and the license plate. It also contains the methods to park/exit the Vehicles from Parking lot.

The Car extends Vehicle class, and it adds additional information: is electric car. The Vehicle class can be eventually extended to add other vehicle types.

```txt

-----------------------------
|          Vehicle          |
|---------------------------|
| + color: string           |
| + brand: string           |
| + height: number          |
| + weight: number          |
| + ticket: Ticket          |
| + isParked: boolean       |
|---------------------------|
| + Vehicle(): void         |
| + parkVehicle(): Ticket   |
| + leaveVehicle(): Vehicle |
-----------------------------
             ^
             |
          Extends
             |

---

| Car | |----------------------------------| | + licensePlate: string | | + isElectricCar: boolean | |----------------------------------|

| + constructor(class_param): void |

```

Parking Lot

The Parking lot is described using a combination between an interface and a class: the interface contains functions signatures, and the concrete class contains an array that is used as a Vehicles container.

```txt

  --------------------------------
  |         <<interface>>        |
  |       ParkingLot<V, T>       |
  |------------------------------|
  | + parkVehicle(vehicle: V): T |
  | + leaveVehicle(ticket: T): V |
  --------------------------------
                ^
                |
             Extends
                |

---

| ParkingLotImpl | |-----------------------------------------| | + address: string | | + maxSize: number | | + availableSlots: array | |-----------------------------------------| | + parkVehicle(vehicle: Vehicle): Ticket |

| + leaveVehicle(ticket: Ticket): Vehicle |

```

How to Use this Project

• Install all dependencies:

sh $ git clone {repo url} $ cd parkinglot-ts-node $ npm install

• Build binary:

sh $ npm build $ npm link

• Run the main program: For interactive mode:

sh $ parkinglot

For file mode: TODO

sh $ parkinglot ./data/inputs.txt

• Run tests cases:

sh $ npm test test/run.testcases.js

Test Inputs:

For interactive mode.

sh create_parking_lot 6 park KA-01-HH-1234 White park KA-01-HH-9999 White park KA-01-BB-0001 Black park KA-01-HH-7777 Red park KA-01-HH-2701 Blue park KA-01-HH-3141 Black leave 4 status park KA-01-P-333 White park DL-12-AA-9999 White registration_numbers_for_cars_with_colour White slot_numbers_for_cars_with_colour White slot_number_for_registration_number KA-01-HH-3141 slot_number_for_registration_number MH-04-AY-1111

Test Outputs:

sh Created a parking lot with 6 slots Allocated slot number: 1 Allocated slot number: 2 Allocated slot number: 3 Allocated slot number: 4 Allocated slot number: 5 Allocated slot number: 6 Slot number 4 is free Slot No. Registration No Colour 1 KA-01-HH-1234 White 2 KA-01-HH-9999 White 3 KA-01-BB-0001 Black 5 KA-01-HH-2701 Blue 6 KA-01-HH-3141 Black Allocated slot number: 4 Sorry, parking lot is full KA-01-HH-1234, KA-01-HH-9999, KA-01-P-333 1, 2, 4 6 Not found

API

• create(numLots: number): number
  • Creates the parking spaces.
  • Input parameters:
  • numLots: number - bound parameter for the parking slot array.
  • Command format: create_parking_lot {number of lots}. Example: create_parking_lot 6.
• parkVehicle(vehicle: V): string
  • Parks a car to the first available slot.
  • Input parameters:
  • vehicle: Vehicle - bound parameter for the vehicle object. Example, a car object that has white color and some licence plate.
  • Command format: park {license plate} {color}. Example: park KA-01-HH-1234 White.
• leave(slot: number): string
  • Remove the cark from parking lot.
  • Command format: leave {slot number}. Example: leave 3.
• status(): string
  • Gets the current status for the parking lot.
  • Command format: status.
• getLicensePlateFromColor(color: string): string
  • Search and get license plate from car color.
  • Command format: registration_numbers_for_cars_with_colour {color}. Example: registration_numbers_for_cars_with_colour White.
• getSlotNumbersFromColor(color: string): string
  • Search and get slot numbers from car color.
  • Command format: slot_numbers_for_cars_with_colour {color}. Example: slot_numbers_for_cars_with_colour White.
• getSlotNumberFromLicensePlate(licensePlate: string): string
  • Search and get slot number from license plate.
  • Command format: slot_number_for_registration_number {licence plate}. Example: slot_number_for_registration_number KA-01-HH-3141.

Plan

• Setup test suite and write comprehensive unit tests.
• Rewrite the command line parser so that it supports both file input and interactive input in one binary.
• A better way to solve the problem is using data structures optimized for complexity.
• Parking lot problem extended - the parking space should accept three different types of vehicles, namely, motorcycle, car, bus.