Flights are a big graph reachability problem with a mass of filters (cabin class, plane type, number of passengers etc) Directs are a trivial problem. 1-stop

Flights are a big graph reachability problem with a mass of filters (cabin class, plane type, number of passengers etc) Directs are a trivial problem. 1-stop indirects is a simplish batch processing problem to produce an easily indexable data set. 2-stop indirects is a huge quantity of computing power.