g For Building::disembarkRider(), if the elevator (whose index is the parameter) has its door open, and also has a rider for the floor where the elevator is currently located, remove one rider from the floor and return true. In all other cases, return false.

Use a physical stopwatch to record the length of time it takes to run the program. calculate the difference obtained by calls to the method system.currenttimemillis() just before the start of the algorithm and just after the end of the algorithm. calculate the difference obtained by calls to the method system.currenttimemillis() at the start of the program and at the end of the program so that the elapsed time includes the display of the result. use the value returned by the method system.currenttimemillis() just after the end of the algorithm as the elapsed time.