Faster 14

1 files changed, 6 insertions, 6 deletions

diff --git a/2021/14.hs b/2021/14.hs
index b088a8f..5059088 100644
--- a/2021/14.hs
+++ b/2021/14.hs
@@ -9,8 +9,8 @@ import Input
 import Util
 
 
-step :: Eq a => [((a, a), a)] -> [a] -> [a]
-step rules (a:b:s) = case lookup (a, b) rules of
+step :: Ord a => Map (a, a) a -> [a] -> [a]
+step rules (a:b:s) = case Map.lookup (a, b) rules of
                        Nothing -> a : step rules (b:s)
                        Just c -> a : c : step rules (b:s)
 step _ l = l
@@ -27,12 +27,12 @@ maphistogram = foldr (\x -> Map.insertWith (+) x 1) mempty
 --   table[p][0][q] = if p == q then 1 else 0
 --   table[p][n][q] = sum over pairs r:
 --                      table[p][n-1][r] * (number of occurrences of q in step(r))
-dyn :: [((Char, Char), Char)]
+dyn :: Map (Char, Char) Char
     -> Int
     -> (Map Char Int, Int, A.Array ((Int, Int), Int, (Int, Int)) Int)
 dyn rules nsteps = (charmap, maxid, table)
   where
-    chars = uniq . sort $ concatMap (\((a,b),c) -> [a,b,c]) rules
+    chars = uniq . sort $ concatMap (\((a,b),c) -> [a,b,c]) (Map.assocs rules)
     charlist = zip chars [0::Int ..]
     charmap = Map.fromList charlist
     maxid = snd (fst (Map.deleteFindMax charmap))
@@ -51,7 +51,7 @@ dyn rules nsteps = (charmap, maxid, table)
                          | otherwise = count (a, b) (y:s)
     count _ _ = 0
 
-solve :: [((Char, Char), Char)] -> String -> Int -> Int
+solve :: Map (Char, Char) Char -> String -> Int -> Int
 solve rules template nsteps =
     let (charmap, maxid, table) = dyn rules nsteps
         inttemplate = map (charmap Map.!) template
@@ -69,7 +69,7 @@ solve rules template nsteps =
 main :: IO ()
 main = do
     template : _ : rules' <- getInput 14
-    let rules = map (\[a,b,' ','-','>',' ',c] -> ((a, b), c)) rules'
+    let rules = Map.fromList (map (\[a,b,' ','-','>',' ',c] -> ((a, b), c)) rules')
     -- let string1 = iterate (step rules) template !! 10
     --     hist1 = Map.elems (maphistogram string1)
     -- print (maximum hist1 - minimum hist1)