In managing how the elevator works in a four-story building, there’s a clear set of steps for moving passengers around. Starting on the 4th floor, the elevator responds when passengers press the buttons with arrows pointing up or down on each floor. For example, if someone on the third floor wants to go down, they press the “Down” button, and the elevator lights it up to show it got the message.

To make things smooth, the elevator decides to go to the closest floor when multiple buttons are pressed. So, if the third and fourth floors both want to go down, the elevator goes to the third floor first because it’s closer. The “Down” button on each floor helps passengers say if they want to go down.

If someone on the fourth floor presses the “Down” button while the elevator is on the third floor, the elevator goes up to the fourth floor. Then, both the third and fourth floors can go down together. Inside the elevator, there’s a button you can press if you want to go down. When the elevator reaches the ground floor, it turns off all the lit-up buttons, including the “Down” button, and opens its doors so people can get out. This plan helps the elevator work well, considering different situations with buttons while making sure people get where they want to go.

The elevator follows these steps:

1. Start on the 4th Floor: The elevator begins its operation on the 4th floor.
2. Respond to Call Buttons: It lights up when someone on any floor presses the “Down” button to indicate a desire to go down.
3. Prioritize Closest Floor: If multiple buttons are pressed, the elevator goes to the closest floor first.
4. Additional Scenarios with Call Buttons: If someone on the fourth floor wants to go down while the elevator is on the third floor, it goes up to the fourth floor to pick them up. Passengers from both the third and fourth floors then go down together.
5. Internal “Down” Button: Inside the elevator, passengers can press the “Down” button to signify their desire to go down.
6. Completion: Upon reaching the ground floor, the elevator turns off all illuminated buttons, including the “Down” button, and opens its doors for passengers to exit.