Elevator Control System

Problem

Design and implement an elevator control system. What data structures, interfaces and algorithms will you need? Your elevator control system should be able to handle a few elevators — up to 16.

You can use the language of your choice to implement an elevator control system. In the end, your control system should provide an interface for:

Build Instructions

• run >sbt compile to generate a jar file

sbt compile

• run >sbt test to runs tests

sbt test

• run >sbt run to run an example

sbt run

Example run:

[info] Running com.cascadeofinsights.skeleton.Main 
List((0,ElevatorState(1,List(Pickup(5,Down), Pickup(3,Down)),Set(),Up)))
List((0,ElevatorState(2,List(Pickup(5,Down), Pickup(3,Down)),Set(),Up)))
List((0,ElevatorState(3,List(Pickup(5,Down), Pickup(3,Down)),Set(),Up)))
List((0,ElevatorState(4,List(Pickup(5,Down), Pickup(3,Down)),Set(),Up)))
List((0,ElevatorState(5,List(Pickup(3,Down)),Set(3),Down)))
List((0,ElevatorState(4,List(Pickup(3,Down)),Set(3),Down)))
List((0,ElevatorState(3,List(),Set(1),Down)))
List((0,ElevatorState(2,List(),Set(1),Down)))
List((0,ElevatorState(1,List(),Set(),Down)))
List((0,ElevatorState(1,List(),Set(),Down)))

Usage

• See tests for sample usage

  it("should not pickup people going the wrong direction") {

      Given("one elevator")
      val system = new ElevatorControlSystem(1)

      When("two Pickup request")
      system.pickup(Pickup(3, Direction.Down))
      system.pickup(Pickup(5, Direction.Down))
      system.step()
      system.step()
      system.step()

      Then("we should not have a passenger")
      val passengers = system.status.head._2.pendingDropOffs
      assert(passengers === Set.empty)
    }

The scheduling problem

Currently a pickup is assigned this way

• If there is an elevator on the way, use it
• else if there is an idle elevator use it
• else use the elevator with the least pending pickups