1) An elevator for a three story building: extend the elevator program to simulate an elevator system for a three floor building.
2) Multiple people: when press the "first/second/third floor" button, multiple people (to say, 3 people) will be placed on the floor (see fig. 1). The elevator, however, can only take one person at a time. i.e., the capacity of the elevator is one person. Therefore, there often will be people waiting on the floor. YOu are asked to add in a "queue" for each floor to hold multiple people, so that the person first come will get a ride on the elevator first (i.e., FIFO)
3) Two elevators: since people complain about too much waiting time, you are asked to add in a second elevator to reduce the waiting time (see fig. 1). The second elevator also has a larger capacity (3 people) than the first elevator ( 1 person ). If possible, the two elevators shall work cooperatively to avoid unnecessary runs.
## Deliverables
1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done.
2) Deliverables must be in ready-to-run condition.
## Platform
any JVM