Day 12 - removed old solution in favour of graph-based solution

12.hs

@@ -1,30 +1,14 @@
 import Data.List.Split (splitOn)
-import Data.IntMap (IntMap, findWithDefault, keys)
-import Data.IntSet (IntSet, member, notMember, insert, delete, empty, size, findMin)
-import qualified Data.IntMap as M (fromList)
-import qualified Data.IntSet as S (fromList, null)
+import Data.Graph (reachable, scc)
+import Data.Array (array)
 
 parseLine :: String -> (Int, [Int])
 parseLine str =
     let src : dests : [] = splitOn " <-> " str
     in  (read src, map read $ splitOn ", " dests)
 
-visit  :: IntMap [Int] -> Int -> IntSet -> IntSet
-visit hashmap node hashset =
-    let neighbours = filter (`notMember` hashset) $ findWithDefault [] node hashmap
-    in  foldr (visit hashmap) (foldr insert hashset neighbours) neighbours
-
-remove :: IntMap [Int] -> Int -> IntSet -> IntSet
-remove hashmap node hashset =
-    let neighbours = filter (`member` hashset) $ findWithDefault [] node hashmap
-    in  foldr (remove hashmap) (foldr delete hashset neighbours) neighbours
-
-countGroups :: IntMap [Int] -> Int -> IntSet -> Int
-countGroups hashmap count hashset = if S.null hashset then count else
-    countGroups hashmap (count + 1) $ remove hashmap (findMin hashset) hashset
-
 main :: IO ()
 main = do
-    hashmap <- fmap (M.fromList . map parseLine . lines) $ readFile "12.txt"
-    print $ size $ visit hashmap 0 empty
-    print $ countGroups  hashmap 0 . S.fromList . keys $ hashmap
+    graph <- fmap (array (0, 1999) . map parseLine . lines) $ readFile "12.txt"
+    print $ length $ reachable graph 0
+    print $ length $ scc graph

12_graph.hs

@@ -1,14 +0,0 @@
-import Data.List.Split (splitOn)
-import Data.Graph (reachable, scc)
-import Data.Array (array)
-
-parseLine :: String -> (Int, [Int])
-parseLine str =
-    let src : dests : [] = splitOn " <-> " str
-    in  (read src, map read $ splitOn ", " dests)
-
-main :: IO ()
-main = do
-    graph <- fmap (array (0, 1999) . map parseLine . lines) $ readFile "12.txt"
-    print $ length $ reachable graph 0
-    print $ length $ scc graph