ElevatorBank

Typically, office buildings have more than just one elevator, for convenience. After all, when you push the button on the ground floor, who really wants to wait a minute for the one elevator in the building to make its way all the way down? However, when you have multiple elevators, collisions may start to occur, where multiple elevators go for the same button press. You have been hired to program new, efficient software for the elevator controller.

The problem is that the elevator must respond on command to the various button presses and cannot know when people will press the button or which buttons will be pressed. Thus, you have decided that the best way to go is to treat each passenger as if he were the final passenger you would have to deal with for the day, no matter whether he is or not.

At time 0 seconds, each elevator starts at floor 1, the ground floor, and is motionless. Each elevator keeps a list of floors that it must stop at, and cannot reverse direction until all of the floors on the list are in the opposite direction to the direction that it is traveling in. When a passenger pushes the call button on some floor, exactly one elevator will be dispatched to that location, the one that would arrive there first of all of the elevators. If there is a tie, dispatch the fastest elevator. If there is still a tie, then dispatch the lowest-indexed elevator.

The process of dispatching works as follows: if the dispatched elevator is motionless, then it adds the relevant floor to its list and moves in the correct direction. Otherwise, it simply adds the floor to its list and keeps moving in the same direction as it was already. If an elevator is motionless and two floors in opposite directions are added to its queue simultaneously, then it should move towards the closer one. If there is no unique closest floor, then set the direction of motion downwards (towards lower-numbered-floors).

When an elevator arrives at a floor that is on its list, it drops off and picks up all the passengers that wish to leave or enter at that floor, respectively, and then it crosses the floor off its list. If passengers are getting on, then the floors they wish to go to are added to that elevator's list. When a given elevator's list contains no more floors, it stops moving.

The elevators may have been installed or refurbished at different times, and thus may have different speeds. secondsPerFloor is a int[] representing the speeds of elevators 0, 1, ... in seconds per floor traveled. passengers is a String[] containing some number of commands from passengers. Each String represents one passenger, and is of the form "CALL f t TO d", where f is the floor that the passenger is at, t is the time at which the call button is pressed, in seconds from the start of the day, and d is the destination floor of the passenger. It is guaranteed that f will not be the same as d, that f and d will be between 1 and 200, inclusive, and that t will be between 1 and 50000, inclusive. In addition, none of them will contain leading zeros.

Before it is put into production, the software must be tested. There are a number of simulated passengers that will be used to test your elevator controller program. Your method should run the elevator controller for the given set of passengers and return an int that represents the number of seconds it will take for all of the passengers to get to their destinations.