Extra credit -

2) As a separate track, looking from a more industrial engineering side of things,...assuming that there is some loss associated with having to produce multiple products at a facility,...could you write a transform that would optimize a list of factories, such that order might be changed in order to optimize production - maybe it makes more sense to let C and D pick up the remaining widgets, instead of splitting up production at B and D,...if I'm making myself clear here. :)