import Data.List.Split (splitOn) import Data.Graph (graphFromEdges, reachable, scc) parseLine :: String -> (Int, Int, [Int]) parseLine str = let src : dests : [] = splitOn " <-> " str in (read src, read src, map read $ splitOn ", " dests) main :: IO () main = do (graph, _, _) <- fmap (graphFromEdges . map parseLine . lines) $ readFile "12.txt" print $ length $ reachable graph 0 print $ length $ scc graph