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#!/usr/bin/env python3
from enum import Enum
class Elevator:
def __init__(self, e_id, floor, goal):
self.id = e_id
self.floor = floor
self.goal = goal
self.dropoffs = []
def direction(self):
if self.goal is None:
return None
if self.goal > self.floor:
return Direction.UP
else:
return Direction.DOWN
def dropoff(self, floor):
if floor in self.dropoffs:
assert self.goal is not None
return
assert floor != self.floor
if self.goal is None:
self.goal = floor
self.dropoffs.append(floor)
else:
direction = self.direction()
if direction == Direction.UP:
if floor > self.goal:
self.goal = floor
self.dropoffs.append(floor)
self.dropoffs.sort()
elif direction == Direction.DOWN:
if floor < self.goal:
self.goal = floor
self.dropoffs.append(floor)
self.dropoffs.sort(reverse=True)
def __repr__(self):
attrs = ', '.join('%s=%s' % t for t in self.__dict__.items())
return 'Elevator(%s)' % attrs
class Direction(Enum):
UP = 1
DOWN = 2
class ElevatorControlSystem:
def __init__(self, num_elevators):
self.elevators = {i: Elevator(i, 1, None) for i in range(num_elevators)}
self.pickup_requests = []
def pickup(self, floor, direction):
self.pickup_requests.append((floor, direction))
def dropoff(self, elevator_id, floor):
self.elevators[elevator_id].dropoff(floor)
def step(self):
# serve pickup requests
free_elevators = list(filter(lambda e: e.goal is None, self.elevators.values()))
while free_elevators and self.pickup_requests:
floor, direction = self.pickup_requests.pop(0)
elevator = min(free_elevators, key=lambda e: abs(e.floor - floor))
elevator.goal = floor
# move elevators to requested floors
for elevator in self.elevators.values():
if elevator.goal is not None:
if elevator.goal > elevator.floor:
elevator.floor += 1
elif elevator.goal < elevator.floor:
elevator.floor -= 1
# check dropoffs and goal after moving
if elevator.dropoffs and elevator.dropoffs[0] == elevator.floor:
elevator.dropoffs = elevator.dropoffs[1:]
if elevator.goal == elevator.floor:
elevator.goal = None
if __name__ == '__main__':
ecs = ElevatorControlSystem(2)
print(' '*4, ecs.elevators)
print('requesting pickup on floor 2 down')
ecs.pickup(2, Direction.DOWN)
ecs.step()
print(' '*4, ecs.elevators)
print('requesting dropoff on floor 1 and pickup on floor 1 up')
ecs.dropoff(0, 1)
ecs.pickup(1, Direction.UP)
ecs.step()
print(' '*4, ecs.elevators)
print('requesting dropoff on floor 3')
ecs.dropoff(1, 3)
ecs.step()
print(' '*4, ecs.elevators)
print('requesting pickup on floor 2 up')
ecs.pickup(2, Direction.UP)
ecs.step()
print(' '*4, ecs.elevators)
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