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@AlexAvlonitis
Last active January 20, 2022 10:27
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Elevator Algorithm in Ruby
# Continue traveling in the same direction while there are remaining requests in that same direction.
# If there are no further requests in that direction, then stop and become idle,
# or change direction if there are requests in the opposite direction.
require 'set'
class Elevator
attr_reader :floors_up, :floors_down
attr_accessor :direction, :current_floor
def initialize(elevator_rules = [ElevatorRule.new])
@elevator_rules = elevator_rules
@current_floor = 3
@direction = :up
@floors_up = SortedSet.new
@floors_down = SortedSet.new
end
def press_floor(floor)
return if current_floor == floor
current_floor > floor ? @floors_down << floor : @floors_up << floor
puts "floors: #{floors_down + floors_up}"
end
def next_floor
@elevator_rules.each { |rule| rule.apply(self) }
end
end
class ElevatorRule
def apply(elevator)
@elevator = elevator
return 'No floors to go' if @elevator.floors_down.empty? && @elevator.floors_up.empty?
set_elevator_direction!
set_current_floor!
end
private
def set_elevator_direction!
@elevator.direction = :up if @elevator.floors_up.any? && @elevator.floors_down.empty?
@elevator.direction = :down if @elevator.floors_up.empty? && @elevator.floors_down.any?
end
def set_current_floor!
if @elevator.direction == :up
next_floor = @elevator.floors_up.min
@elevator.current_floor = next_floor
@elevator.floors_up.delete(next_floor)
elsif @elevator.direction == :down
next_floor = @elevator.floors_down.max
@elevator.current_floor = next_floor
@elevator.floors_down.delete(next_floor)
end
puts "current_floor: #{@elevator.current_floor}"
end
end
e = Elevator.new
e.press_floor(1)
e.press_floor(3)
e.press_floor(5)
e.press_floor(8)
e.next_floor
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