Cleanup 15

1 files changed, 8 insertions, 35 deletions

diff --git a/2021/15.hs b/2021/15.hs
index 542ba42..271a49d 100644
--- a/2021/15.hs
+++ b/2021/15.hs
@@ -9,8 +9,6 @@ import Data.Function (on)
 import Data.List hiding (insert)
 import Data.Ord
 
--- import Debug.Trace
-
 import Input
 
 
@@ -32,55 +30,33 @@ qAdds = \pairs (PQueue l) -> PQueue (inserts (let PQueue pq = qFromList pairs in
           LT -> (k, vs) : inserts restnews l
           EQ -> (k, vs ++ vs') : inserts restnews rest
           GT -> (k', vs') : inserts news rest
-qAdd :: Ord k => k -> v -> PQueue k v -> PQueue k v
-qAdd k v pq = qAdds [(k, v)] pq
 qPop :: PQueue k v -> Maybe ((k, v), PQueue k v)
 qPop (PQueue []) = Nothing
 qPop (PQueue ((k, [v]) : l)) = Just ((k, v), PQueue l)
 qPop (PQueue ((k, v:vs) : l)) = Just ((k, v), PQueue ((k, vs) : l))
 qPop (PQueue ((_, []) : l)) = qPop (PQueue l)
 
--- Return array: (parent position, minimal distance)
-dijkstra :: A.Array (Int, Int) Int -> A.Array (Int, Int) ((Int, Int), Int)
+dijkstra :: A.Array (Int, Int) Int -> A.Array (Int, Int) Int
 dijkstra board = MA.runSTArray $ do
-    arr <- MA.newArray (A.bounds board) ((-1, -1), maxBound)
-    MA.writeArray arr (0, 0) ((-1, -1), 0)
+    arr <- MA.newArray (A.bounds board) maxBound
+    MA.writeArray arr (0, 0) 0
     loop arr (qFromList [(0, (0, 0))])
     return arr
   where
-    loop :: MA.STArray s (Int, Int) ((Int, Int), Int) -> PQueue Int (Int, Int) -> ST s ()
+    loop :: MA.STArray s (Int, Int) Int -> PQueue Int (Int, Int) -> ST s ()
     loop arr qu
       | Just ((curdist, (x, y)), qu') <- qPop qu = do
-          -- traceM ("pq = " ++ show qu)
-          -- traceM ("visit " ++ show (x, y))
-          -- traceM ("pq = " ++ show qu')
-          neighbours <- mapM (\pos -> (pos,) . snd <$> MA.readArray arr pos)
+          neighbours <- mapM (\pos -> (pos,) <$> MA.readArray arr pos)
                         . filter (A.inRange (A.bounds board))
                         $ [(x+1,y), (x,y+1), (x-1,y), (x,y-1)]
           let updates = [(curdist + board A.! pos', pos')
                         | (pos', dist) <- neighbours
                         , dist > curdist + board A.! pos']
-          -- traceM ("updates = " ++ show updates)
           forM_ updates $ \(newdist, pos') ->
-              MA.writeArray arr pos' ((x, y), newdist)
-          -- MA.freeze arr >>= traceM . printDists
+              MA.writeArray arr pos' newdist
           loop arr (qAdds updates qu')
       | otherwise = return ()
 
-printDists :: A.Array (Int, Int) ((Int, Int), Int) -> String
-printDists dists =
-    let pad2 s = let s' = "  " ++ s in drop (length s' - 2) s'
-        (_, (ymax, xmax)) = A.bounds dists
-    in unlines [intercalate " " [let d = snd (dists A.! (y, x))
-                                 in if d == maxBound then "--" else pad2 (show d)
-                                | x <- [0..xmax]]
-               | y <- [0..ymax]]
-
-tracePath :: A.Array (Int, Int) ((Int, Int), Int) -> (Int, Int) -> [((Int, Int), Int)]
-tracePath _ (-1, -1) = []
-tracePath dists to = let (next, dist) = dists A.! to
-                     in (to, dist) : tracePath dists next
-
 expand :: Int -> (Int -> a -> a) -> A.Array (Int, Int) a -> A.Array (Int, Int) a
 expand times f arr =
     let ((0, 0), (ymax, xmax)) = A.bounds arr
@@ -95,9 +71,6 @@ main = do
     board <- map (map (read . pure)) <$> getInput 15
     let (h, w) = (length board, length (head board))
     let boardarr = A.listArray ((0, 0), (h-1, w-1)) (concat board)
-    print (snd (dijkstra boardarr A.! (h-1, w-1)))
+    print (dijkstra boardarr A.! (h-1, w-1))
     let expanded = expand 5 (\n x -> (x + n - 1) `mod` 9 + 1) boardarr
-    -- putStr $ unlines [concatMap show [expanded A.! (y, x) | x <- [0 .. 5*w-1]] | y <- [0 .. 5*h-1]]
-    print (snd (dijkstra expanded A.! (5*h-1, 5*w-1)))
-    -- mapM_ print $ reverse (tracePath dists (h-1, w-1))
-    -- putStr (printDists dists)
+    print (dijkstra expanded A.! (5*h-1, 5*w-1))