This is a similar problem to figuring out search results when you try to find an airline reservation. It's a problem people have been working on for almost 50 years and it still works, although there are a lot of likely shortcuts. I also remember we had some kind of system that tried to optimize pricing and schedules for airlines which which ran for days sometimes (this was in 2000 or so). I think modern hardware is much better and allow algorithms that are much more capable. I wonder how you test something this complex that is never actually done; how do you know its working optimally (or at least acceptably)?