import Data.Map
import Data.Char
import Text.Regex.Posix

cRoutes g [] _ _ _ = []
cRoutes g (n:ns) p v rc
    | n == "end"       = [p ++ ["end"]] ++ cRoutes g ns p v rc
    | isUpper (n !! 0) = cRoutes g (g ! n) (p++[n]) v rc ++ cRoutes g ns p v rc
    | notElem n v      = cRoutes g (g ! n) (p++[n]) (n:v) rc ++ cRoutes g ns p v rc
    | rc == "" && n /= "start"  = cRoutes g (g ! n) (p++[n]) v n ++ cRoutes g ns p v rc
    | otherwise        = cRoutes g ns p v rc

generateGraph [] m = m
generateGraph (g:gs) m = let [[_,from,to]] = g =~ "(.*)-(.*)" :: [[String]]
                         in generateGraph gs $ insertWith (++) from [to] $ insertWith (++) to [from] m

main = do fileContent <- readFile "day12.in"
          let linesOfFile = lines fileContent
              graph = generateGraph linesOfFile Data.Map.empty
          print $ length $ cRoutes graph ["start"] [] [] "."
          print $ length $ cRoutes graph ["start"] [] [] ""