$(24$ points$)$ Design a simple elevator light controller: each floor has an up and a down button to call the

elevator and an up and a down light to indicate that the elevator is coming in that direction. The light

should turn on when the corresponding button is pressed, then turn off after the elevator passes the floor

in the requested direction.

For simplicity, there is an up button on the top floor and a down button on the bottom floor; neither will be

pressed. Floors are numbered $0($bottom floor$)$ to $9($top floor$).$