removed some import statements and added another (failing) local test
added more explicit graph implementation to GalaxyTrip
changed functionality of GalaxyTrip to use graph implementation instead of map
GalaxyTrip passes 20/62 tests
moved calculation of graphSizes to its own function
GalaxyTrip passes 17/62 tests
GalaxyTrip passes 17/62 tests
GalaxyTrip passes 24/62 tests
GalaxyTrip passes 28/62 tests