How should I practice Elevator Scheduling Simulation?

Start by reading the full statement, solve the visible examples, then compare the pattern against related OpenAI phone screen problems in FastPrep.

Is Elevator Scheduling Simulation associated with OpenAI?

FastPrep tags this as a OpenAI phone screen coding practice problem when the problem catalog has that company and stage context.

Elevator Scheduling Simulation

OpenAI● MediumFULLTIMENEW GRADPHONE SCREEN

Problem statement

Source note: The interviewer's task said: "We're going to implement a simple elevator simulation for a building with one elevator. The elevator travels up to the top floor, then down to the bottom floor, repeating this route. Along the way, it stops to drop off passengers at their destinations and pick up passengers traveling in its current direction." Part 2 said: "Now we'll let the elevator turn around sooner, based on where passengers need service."

The candidate saw Python starter files and a do_tick(building) function to write, but the tests and data files were not shared, and the candidate never reached Part 3, so Part 3 is not here. You get one function that returns a row per tick instead of do_tick. The report does not say which floor the elevator starts on, whether it has a capacity limit, or what it does in Part 2 when nobody needs it. Part 2 as written says to turn when nobody is ahead, but its FAQ says a passenger going the current way still boards. Here, the elevator starts on floor 0 with no capacity limit. In Part 1 the switch at the top or bottom floor happens before the stop check. In Part 2 the whole stop check comes first, so a tick where a rider gets out or someone boards the current way never changes direction, and a waiting passenger counts as service ahead whichever way they go. The report could also be read so that only someone boarding the current way comes before the turn, which would let a drop-off tick turn and board the other way at once. This version does not do that. Turning takes no time, so someone going the new way boards in the turning tick. With nobody to serve, the Part 2 elevator stays put and keeps its direction. An empty calls entry means nobody arrives. The size limits are practice choices.

The judged task matches the report at about 80%.

Simulate one elevator in a building with numFloors floors, numbered 0 to numFloors - 1. The elevator starts on floor 0 with direction UP and has no capacity limit. Return what it does in each tick.

How time works

Time moves in discrete steps called ticks. In each tick the elevator can do one of these:

Move up or down exactly one floor.
Stop to drop off passengers, board passengers, or both.

Either action takes a full tick, so the elevator cannot move and drop off or board in the same tick. Many passengers can get off and board during one stop. Changing direction takes no time. Passengers who reach their destination leave the simulation.

The problem statement continues

Pro

Examples

Example 1

numFloors = 4calls = ["0,2;0,3"]part = 1return = [[0,0,2],[1,0,0],[2,0,0],[2,1,0],[3,0,0],[3,1,0]]

This is the walk-through from the task. The elevator is on floor 0 going up, and two passengers wait to go to floors 2 and 3.

Board the passengers on floor 0: [0,0,2].
Move to floor 1: [1,0,0].
Move to floor 2: [2,0,0].
Drop off the passenger going to floor 2: [2,1,0].
Move to floor 3: [3,0,0].
Drop off the passenger going to floor 3: [3,1,0].

Each step takes one tick. Everyone is done, so the simulation ends after six ticks.

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