It's probably best to use a E*N entry LRU cache for elevator requests. In the morning it's going to be predominantly ground floor to upper floors, a complete mi

It's probably best to use a E*N entry LRU cache for elevator requests. In the morning it's going to be predominantly ground floor to upper floors, a complete mix during lunch, and in the afternoon upper to lower, by using the E floors that have most entries in the LRU cache you'll be able to fairly efficiently move the elevators to the correct floors most of the time, and also account for any discrepancies in office hours. (E = the number of elevators, N probably should be the number of floors, no idea what would make a good N) I'm sure that if you snap shotted the LRU cache every few minutes you could build a pretty good predictive index for the patterns through out the week and time of day. What might be interesting would be wifi/cell signal detectors that could pick up a cell when it enters the hallway and start moving the elevator already.