That's were all the task for the simple lift controller. Below you find a solution for the last task.
But there is always room for improvements. Here are just some examples one could do to improve or expand the lift controller:

*   Use more appropriate data structures like a queue
*   Parsing the <a href="https://oer.wr.informatik.uni-hamburg.de:8000/courses/1/4/57/">command-line arguments</a> to determine the requests
*   Change it to work with arbitrary amounts of time-steps
*   Implement different phases like moving to a different floor and waiting at a floor with a <a href="https://en.wikipedia.org/wiki/Automata-based_programming">State Machine</a>

This is just some ideas we have you could try, if you gathered more experience. For that you could try out the C-Basic course or find
coding resources on your own.