Design an elevator system
Medium45 minFree, no account
Two kinds of request, four elevators, and a scheduling policy you have to defend.
The question
Design the control system for a bank of four elevators in a twenty-storey building.
Be specific about how a hall call is assigned and what happens to a car already in motion.
Functional
- Hall calls (a floor, a direction) and car calls (inside, a destination).
- Assign hall calls to a car; cars serve their stops efficiently.
- Doors open, hold, and close; obstruction reopens them.
- Emergency stop and maintenance mode.
Non-functional
- No request is ignored indefinitely.
- Scheduling policy swappable without touching car control.
45:00Commit to an answer before you open the solution. Reading it first teaches you to recognise good answers, which is not the skill being tested.
Stuck?
0 of 3 hints takenThe worked solution
written by a person · not a gradeScore yourself
0 of 5 marked- Separated hall calls from car calls and dispatch from car control25
- Gave a per-car scheduling algorithm, not just a queue20
- Compared dispatch policies and made the policy swappable25
- Addressed starvation explicitly20
- Modelled doors, maintenance and emergency as real states10
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