-allDistances gs = case S.minView gs of
- Nothing -> 0
- Just (g, gs') -> (S.foldl' (addDist g) 0 gs) + allDistances gs'
- where addDist g1 acc g2 = acc + distance g1 g2
+allDistances gs = snd $ S.foldl' addGalaxy (S.empty, 0) gs
+ where addGalaxy (seen, d) new =
+ (S.insert new seen, S.foldl' (addDist new) d seen)
+ addDist g1 d g2 = d + distance g1 g2