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Add Parking Lot Solution

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Donne Martin 2017-03-03 18:54:23 -08:00
parent 616710f42e
commit 831906f96c
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solutions/object_oriented_design/parking_lot/__init__.py Normal file
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solutions/object_oriented_design/parking_lot/parking_lot.ipynb Normal file
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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer-primer)."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Design a parking lot"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Constraints and assumptions\n",
"\n",
"* What types of vehicles should we support?\n",
" * Motorcycle, Car, Bus\n",
"* Does each vehicle type take up a different amount of parking spots?\n",
" * Yes\n",
" * Motorcycle spot -> Motorcycle\n",
" * Compact spot -> Motorcycle, Car\n",
" * Large spot -> Motorcycle, Car\n",
" * Bus can park if we have 5 consecutive \"large\" spots\n",
"* Does the parking lot have multiple levels?\n",
" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Solution"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Overwriting parking_lot.py\n"
]
}
],
"source": [
"%%writefile parking_lot.py\n",
"from abc import ABCMeta, abstractmethod\n",
"\n",
"\n",
"class VehicleSize(Enum):\n",
"\n",
" MOTORCYCLE = 0\n",
" COMPACT = 1\n",
" LARGE = 2\n",
"\n",
"\n",
"class Vehicle(metaclass=ABCMeta):\n",
"\n",
" def __init__(self, vehicle_size, license_plate, spot_size):\n",
" self.vehicle_size = vehicle_size\n",
" self.license_plate = license_plate\n",
" self.spot_size\n",
" self.spots_taken = []\n",
"\n",
" def clear_spots(self):\n",
" for spot in self.spots_taken:\n",
" spot.remove_vehicle(self)\n",
" self.spots_taken = []\n",
"\n",
" def take_spot(self, spot):\n",
" self.spots_taken.append(spot)\n",
"\n",
" @abstractmethod\n",
" def can_fit_in_spot(self, spot):\n",
" pass\n",
"\n",
"\n",
"class Motorcycle(Vehicle):\n",
"\n",
" def __init__(self, license_plate):\n",
" super(Motorcycle, self).__init__(VehicleSize.MOTORCYCLE, license_plate, spot_size=1)\n",
"\n",
" def can_fit_in_spot(self, spot):\n",
" return True\n",
"\n",
"\n",
"class Car(Vehicle):\n",
"\n",
" def __init__(self, license_plate):\n",
" super(Car, self).__init__(VehicleSize.COMPACT, license_plate, spot_size=1)\n",
"\n",
" def can_fit_in_spot(self, spot):\n",
" return True if (spot.size == LARGE or spot.size == COMPACT) else False\n",
"\n",
"\n",
"class Bus(Vehicle):\n",
"\n",
" def __init__(self, license_plate):\n",
" super(Bus, self).__init__(VehicleSize.LARGE, license_plate, spot_size=5)\n",
"\n",
" def can_fit_in_spot(self, spot):\n",
" return True if spot.size == LARGE else False\n",
"\n",
"\n",
"class ParkingLot(object):\n",
"\n",
" def __init__(self, num_levels):\n",
" self.num_levels = num_levels\n",
" self.levels = []\n",
"\n",
" def park_vehicle(self, vehicle):\n",
" for level in levels:\n",
" if level.park_vehicle(vehicle):\n",
" return True\n",
" return False\n",
"\n",
"\n",
"class Level(object):\n",
"\n",
" SPOTS_PER_ROW = 10\n",
"\n",
" def __init__(self, floor, total_spots):\n",
" self.floor = floor\n",
" self.num_spots = total_spots\n",
" self.available_spots = 0\n",
" self.parking_spots = []\n",
"\n",
" def spot_freed(self):\n",
" self.available_spots += 1\n",
"\n",
" def park_vehicle(self, vehicle):\n",
" spot = self._find_available_spot(vehicle)\n",
" if spot is None:\n",
" return None\n",
" else:\n",
" spot.park_vehicle(vehicle)\n",
" return spot\n",
"\n",
" def _find_available_spot(self, vehicle):\n",
" \"\"\"Find an available spot where vehicle can fit, or return None\"\"\"\n",
" # ...\n",
"\n",
" def _park_starting_at_spot(self, spot, vehicle):\n",
" \"\"\"Occupy starting at spot.spot_number to vehicle.spot_size.\"\"\"\n",
" # ...\n",
"\n",
"\n",
"class ParkingSpot(object):\n",
"\n",
" def __init__(self, level, row, spot_number, spot_size, vehicle_size):\n",
" self.level = level\n",
" self.row = row\n",
" self.spot_number = spot_number\n",
" self.spot_size = spot_size\n",
" self.vehicle_size = vehicle_size\n",
" self.vehicle = None\n",
"\n",
" def is_available(self):\n",
" return True if self.vehicle is None else False\n",
"\n",
" def can_fit_vehicle(self, vehicle):\n",
" if self.vehicle is not None:\n",
" return False\n",
" return vehicle.can_fit_in_spot(self)\n",
"\n",
" def park_vehicle(self, vehicle): # ...\n",
" def remove_vehicle(self): # ..."
]
}
],
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solutions/object_oriented_design/parking_lot/parking_lot.py Normal file
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from abc import ABCMeta, abstractmethod
class VehicleSize(Enum):
MOTORCYCLE = 0
COMPACT = 1
LARGE = 2
class Vehicle(metaclass=ABCMeta):
def __init__(self, vehicle_size, license_plate, spot_size):
self.vehicle_size = vehicle_size
self.license_plate = license_plate
self.spot_size
self.spots_taken = []
def clear_spots(self):
for spot in self.spots_taken:
spot.remove_vehicle(self)
self.spots_taken = []
def take_spot(self, spot):
self.spots_taken.append(spot)
@abstractmethod
def can_fit_in_spot(self, spot):
pass
class Motorcycle(Vehicle):
def __init__(self, license_plate):
super(Motorcycle, self).__init__(VehicleSize.MOTORCYCLE, license_plate, spot_size=1)
def can_fit_in_spot(self, spot):
return True
class Car(Vehicle):
def __init__(self, license_plate):
super(Car, self).__init__(VehicleSize.COMPACT, license_plate, spot_size=1)
def can_fit_in_spot(self, spot):
return True if (spot.size == LARGE or spot.size == COMPACT) else False
class Bus(Vehicle):
def __init__(self, license_plate):
super(Bus, self).__init__(VehicleSize.LARGE, license_plate, spot_size=5)
def can_fit_in_spot(self, spot):
return True if spot.size == LARGE else False
class ParkingLot(object):
def __init__(self, num_levels):
self.num_levels = num_levels
self.levels = [] # List of Levels
def park_vehicle(self, vehicle):
for level in levels:
if level.park_vehicle(vehicle):
return True
return False
class Level(object):
SPOTS_PER_ROW = 10
def __init__(self, floor, total_spots):
self.floor = floor
self.num_spots = total_spots
self.available_spots = 0
self.spots = [] # List of ParkingSpots
def spot_freed(self):
self.available_spots += 1
def park_vehicle(self, vehicle):
spot = self._find_available_spot(vehicle)
if spot is None:
return None
else:
spot.park_vehicle(vehicle)
return spot
def _find_available_spot(self, vehicle):
"""Find an available spot where vehicle can fit, or return None"""
# ...
def _park_starting_at_spot(self, spot, vehicle):
"""Occupy starting at spot.spot_number to vehicle.spot_size."""
# ...
class ParkingSpot(object):
def __init__(self, level, row, spot_number, spot_size, vehicle_size):
self.level = level
self.row = row
self.spot_number = spot_number
self.spot_size = spot_size
self.vehicle_size = vehicle_size
self.vehicle = None
def is_available(self):
return True if self.vehicle is None else False
def can_fit_vehicle(self, vehicle):
if self.vehicle is not None:
return False
return vehicle.can_fit_in_spot(self)
def park_vehicle(self, vehicle): # ...
def remove_vehicle(self): # ...