Solve day 20

Sneaky bastard, that Eric

Author: Demindiro

2021/20/Main.hs

@@ -0,0 +1,60 @@
+import Data.List.Split (splitOn)
+import qualified Data.Vector as V
+import qualified Data.Set as S
+
+data Pixel = Light | Dark deriving (Eq, Show)
+data Image = Image Int Int (S.Set Point) Pixel
+type Enhancer = V.Vector Pixel
+type Point = (Int, Int)
+
+instance Show Image where
+  show (Image r c im b) = foldr ((++) . ('\n':)) "" f
+    where f   = map g [-3..r+2]
+          g y = [ if S.member (x, y) im then v else v' | x <- [-3..c+2]]
+          [v, v'] = if b == Dark then "#." else ".#"
+
+inv Light = Dark
+inv Dark  = Light
+
+binToDec :: [Pixel] -> Int
+binToDec = f 0
+  where f n []      = n
+        f n (Dark :s) = f (n * 2 + 0) s
+        f n (Light:s) = f (n * 2 + 1) s
+
+parseEnhancer :: String -> Enhancer
+parseEnhancer = V.fromList . f
+  where f []       = []
+        f ('.':es) = Dark  : f es
+        f ('#':es) = Light : f es
+
+sample :: Point -> Image -> Int
+sample (x, y) (Image _ _ im bs) = binToDec $ reverse l
+  where f p = if S.member p im then inv bs else bs
+        l   = [f (x-x',y-y') | y' <- [-1..1], x' <- [-1..1]]
+
+enhance :: Enhancer -> Image -> Image
+enhance eh im@(Image r c _ bs) = Image (r + 2) (c + 2) (S.fromList im') bs'
+  where im' = [ (x,y)
+              | y <- [0..r + 2]
+              , x <- [0..c + 2]
+              , eh V.! sample (x - 1, y - 1) im /= bs'
+              ]
+        bs' = if eh V.! 0 == Dark then bs else inv bs
+
+pixelsInImage (Image _ _ im _) = S.size im
+
+enhance' 0 eh im = im
+enhance' i eh im = enhance' (i - 1) eh $ enhance eh im
+
+main = f <$> splitOn "\n\n" <$> readFile "input.txt"
+   >>= \(eh,im) -> mapM_ (print . pixelsInImage)
+                         [enhance' 2 eh im, enhance' 50 eh im]
+  where f [eh, im] = (parseEnhancer eh, g $ lines im)
+        g im@(r:_)  = Image (length im) (length r) (h im) Dark
+          where h = S.fromList
+                  . map (\(y,x,_) -> (x,y))
+                  . filter (\(_,_,v) -> v == '#')
+                  . foldMap (\(y,l) -> map (\(x,v) -> (y,x,v)) l)
+                  . zip [0..]
+                  . map (zip [0..])

2021/20/input.txt

@@ -0,0 +1,102 @@
+###.#####..###..###.....##.##.#..#.#######..#...####.....#.#.###..##.#....####.#...##.#.#..##.###..######.#.#.#.##..#...##..###....####.##.##..#.#..##...##.#..#..#...#..#....###.####.######..#..#..#..#..........#.####...#..####.##.....#.#..#..#..####.##..#...####..#....#...##.#####...##.#.##.#..#....###....###..#...#....###.#....#..##....#..#..#..#..#.......###..##..##..####...###..#.....######.#.#.#.####.####.#####.....#..#...#.#.###...#...#.##.##.....#....#..##.###..#.##.#.##..#.#......####.#....#..#.#...
+
+...#.####...#...#..#####..#.#.##........###..#.....##..####.###.#####......#.##.#..###.#####..#..###
+#...#.#....####.##.#...###..##...#.###...###...#..#.##.#.###..#.#.##..#.####.#..#..#.####.##.#..#...
+....#.##..##.#####.#...#########..#.#.####....#..#.#..##.##.###.#.####.##.###.##...#.######..#.#.#..
+..#.##.###.##..#.###..#.#..#.#..###..........#..#..###.#.......###.##.#.#..#####.##.###.###.###..#.#
+##...#...#.###.#####..#.#####.#..##.#.##.#..#.##.#..#...##...####.#.#..#....#########.#.##...####.##
+###.##...#.###...#.####...#.#.##..##......##..#.###..#####..##...##.##..##..##.##...#.#.#..#.#..##..
+.#.#####....#...#...#..##..##..#....#..##..##.##..#..#.##..#.#.###..##..###..#...#....##.##...##.###
+.##.#..#####.##.#.#..#..#.#####.....##.####.....#######.#.####.####..#.#.###.#....###.#...##..#.#.##
+#.#.#..###..###.#.###..###...##.##.#....##.#.###..######....##.##......##.#..#..######.###.##..###..
+#..######..##..####..#.#....#...#.#.###....###....#.#..##.###.#..#.#..#.##.#....#....#....##..##....
+.##....#...###...##..#...#....##.####..#.##..#.....#....####.#..#...##.#..###.#.#.####....##.#...###
+##.#######...###...........##.###..##..######..###..#.##.###..#.##...#.####...#....###.#..#.##.###.#
+.#..#..#..#...###....#.#..#.####.#.#....###...#.#...#..##.##..#...###.#.#.....#.#.#.###....###.#...#
+###..##.####..####.#.##..#..#.######.#.#####....#..#.#......#........#.#..##.#.####...###.#..#.##..#
+.##.#.####.#.##.###..#..#....#####.#.....#..#....###.....#.#..######..#..#....#.##....####.###.#.##.
+.#..#.....##....#.#.#...######...####.#####..#.#.#.##.#..#####.#.#.#.##..#..##.##.......##..#.#.##..
+###..##...####....##.#...#..##.##.###.#......##...##.....#.#.#.....#.###.##..####..##.####.#.###.###
+..#...#...####.....####.#.#.#..##..##..#....##.##.###.#.#####.#..##.##.##...##..#.###..#.#...##....#
+.#.##.#..####.#.#..##...#......###.#..##.##.........####.###.#..##.####..#.#.#.#.###...#.#...##.##.#
+##.#..#...##.##.##.#...###.....##.#####.#.#.##...#.#.###..#.##..#.##...#...#..#..#..####..##..###..#
+...#####.##..##.###.#.#..###......#..##..#..#######.#.#.......##.#.#.###.##.#.#.####...##.#..#....##
+#.#...########.##.#.#..####.###.####.##.#####..##.###.#.#.###...#....##..#..###.#.....#.###.##.....#
+.#.##.##.##...#####..##..##.###.######.......#.#.#....##.###..###..##.###.#.#..#..#..####...#..#.#..
+##.###.###....########....#.#...###..#.##.#....###..#.#.....###..#.#..#.##.#.......######.#.#.##....
+##.#.##..#....#.#..##.#.###.##...####.....#...#.#######....#..#.#.#.#.#..#.#.#.##.####..#..#...###..
+.#.######.##.#..#..###.#.###..#.#.#..#...#..##.#######.#...#...#..####.#....###...#.###.##...##....#
+.#.##.#.#.#..#..#.####.##..####..#..###.#.##..#..##........#.#.#.#########.#..####..#..#.##.##....#.
+..###.#..##.##.##...###.##...##.##.##.#.##.###.#####.##..#####.##..######..####.##.#.##..#.....##...
+##..####..#.##....##.#..##..#.#.#..#.##.....#..#....#.#.###.##.##.####.##....#.#.##......#....#.....
+..#.......#.#....##.#.#.###..####..###..#.#.####.....#...#..##.#..#..#...######...........##..##...#
+...#.#...#....##.#....##.##.##.#.#..#.##.#.###.#.#.#.#.#######.#.##.##..#..##.#.....#..##..#.##.#...
+.#.#..#..#..##..#....#.#..#....##....#.###.###...#..#...####.###.....#.##.#..###.....##..#.#.##..#..
+.#....##..##..#..#...##.##.#.##..#.##.#.#...#####..#....##...##...#...####.###.#..#####.#..##..#..##
+###.#####.#.#...#.#.#######.#.....#####.#...#..#.##.###...#..#..#.#..##..#.#...###.##.#..##..###.#.#
+.#####.###.#######..#.#......#.##.#.##.#.#...##....##.#.#.#...#..#....##...#..#...#...###....#..#.##
+###...##.##.##.##..####.##.######.#.######.##..#.#...##...#....####...#..##....#..#..#####....#.#..#
+#...###.#.#.###...####...##.#.#..###..#######.##.####..#.####..##.#.##.###.######.........###.#.#.##
+####.###.#.#.#.####...#..#..######.#..####..##.#.###...#.#.#.##....#..#.#.##.#..#....#...##.##..###.
+#...#..##.#...#..##..##.####.#..###.##.#...#.#.#...##.##.#.#....##...###.#...#...#..#.#.#.##.##....#
+...#...###...#..######.#.####.#.#..####.....#.####..###.#.######..##.......##.#...#..##..#.###..###.
+.##.##.##..#..###.#...##..#.#.#..##..###.#.###.#.#.##.....#.#.###....#.#..##.##..##.###.###.####..##
+###.###....####..#..#.##.#.#..#.####..##.##.#..##..##.#.#.#.##..###...#.#.##.#..##.##..#.#..##.##.##
+##...####.##.##...#.###...##..#.##..#.##...####..###.....#.##.#.##.#.#....###.........#.#.#..###.###
+.#..##.###..##.#..#.#####......#..#####.#.###...###.#....##...#####..###.####.###..##.#.#...#...#.#.
+..#...#..####....#..#......#.##...######.##.###.##.##.##.#......#####.#..##.#...##...###..###...####
+..#..###.####.####.####.###..##...#########....######..#....##.###...#.#........##...##...#..##..###
+.##..#......###.#...##.#..#.#..####.###.#.###..##.##.#...###.#.....##..#..#.#.#..#......#.####.##.#.
+###..##.#.#.###..#....#.##.###.........#.##...#.###...##...#.##....#.#.#.#..###....###.###..#.##...#
+###.#..##.#...####..##..##.#...#.##..#..##.####.#..#.#.#..#.##....#..#......###....####......#.#...#
+.#######...###...###.##.#.#..#.....##...#...#.####..##.#.##..#.#...#..###........##..##.#.##..#.....
+..####.#####...##..##.###.##.#..#..##...#.#....##.#.#...##...###...##.#....###.#.##....#.....#.#.#.#
+...#.......#..#.###.....##.#.......#...#..##....#####.##.###.....##....##.#....#.#.##.#.#.#..####.#.
+.#..#.#..#...#.#.#..#..#..###..#####..###.#.#.####.##..#.#....####.##...#...#....##..##.##...###.#.#
+.#.##..#######..#.......#.###..#.#.###.#..##.##......##.####.##.###......#.###.#.#...#...##.....##..
+#..####.....#..#...###.#.###..#...#.###.#...###...##.##....##.##..#.###.###.###.#.##...####.#.##.##.
+.###.....#####.##.#...####..#.##..###########..#...######.......###.......####.###....#.###.....###.
+.#.####..#..#.##...#.#######.#.###....#.###.#..#.#.#..##.#.#.#..#.#.#.....#..#..###..##..#....####.#
+.#####..#..#....#.###.#.###...#.###..#.#.##.#....#.####...##....##.#####.####.##..#.#.#####..####.##
+#...##....###..###...##...#..#......#..#.##..####..##.#.#......#..##.#..##..###.##..###...#..####.##
+....####.####..........#...#..####..#.....#....##.####.#.##..#..#....##...#.#...##.#.#..##.##.##...#
+.....#.#...#...#.###..#..#.#....#....#..#.###.##.#.##.##..#.#.....#.###....####.#....#.....#.#..#.##
+#...#.##..#.#..##.#.....#.#.#.#..#.####..#...#.#.#...##.....#.#####..##..##..###.##.#....#.....#....
+.####.##..##.......##.####..##......##...#.#.###..#.....##.#..#.##.#.#.#.###.......###.##.#.........
+#.###.#.#.###.#.#.#..##.#..#.######..#...#....#..###.##.#...#.#.#.#.####....##..###.###....#.#.###..
+.#.#..#.....####.#####..##..####....###....#....##.##......##..#.#.#...#.#...##.##.##.######.#.#.###
+###..#.#..###..#..##..###.....#####.#.#...#.##......#.#.#........#.#...#.....##..##...#.#....#.#..#.
+##....#####...#.#..###.####...#...##....##..#.#...#...##.##...##........#.#....#####..#.....####..#.
+.#..#.#####.#...#.#.#..###.##...##...##..##......##.#.###...#.#..#.#####.#.#..##...##..##...###.....
+.##..#..##..#.###..####.....##.#..##.#.#...##.#########..#..###..#.##.#.#..#.#.#.###.###..####..##.#
+##..#..#...#..##...#.#.##...#....##..#.#.##.....##.#####.##..##....#.#......#.###.....#.###.....#...
+#.#.#..#..##...#.##.##.###.###......#...###....#.#..##..#.##..#..#.##.#####...#...###.#####..#...###
+...#..##.######.#..#..##..#..##..#....#.#.#..#...#.##....##.#.##.##....###.#.######..#..###...##.#..
+###...######..#.##.##.#.#.###.#.#.#...###.##...##.#.##.#.#.#..#....####...###.#..##.##.#.##..#..#..#
+#.##..###.######..#..#.##.##.#.##..##..#.##..#.##..##.######.#.#....#.#...#...##..#.#.##.#.#...#.#.#
+..##.#.#...###.##.....#.#.#.#.#####..###.#..##..##.#.#..##.#.###..#..#.##....#....##...#######.#.#.#
+.#.###.....#..#.#.....#..#.....#....#....##..###.##.##.#.#####....#.####.....##....#.####.#.##...##.
+#.####.##..#..#....###.#.......####..##.##..##...#...#..##..##.#...#.#..#..#.##.##.#..########..####
+.###.#.#..#######...#.#.###.#.#.##.....#.#..##.#..##..#.#....##..##..##..##.#.#.#..#.#..#.#...#..#..
+###.#.#.#....#.#..#..###..#..#.####.#.#....#.#####..#.####.#.##.#######.##...###.#...#..#.####..###.
+.#.....###.##.##..#..###...####....####...#..#...###..##...##.###.###..#.##.#.#.####.....##.#.......
+.#..##.#.#...##.#..........##.####.#.###..##....#.....#.####........#.#.#.##.##.##.#...##..#..###...
+#.#.###.###..#.##..#.##..##...#..#.......####...#.#..#...##.#.##...#..##.###.####.#......#.......###
+..###..#..####.#.#...#..###..#.#.#...#####..#..#####..#.......#.#..#.###..#..#.##.######.###.#.#..#.
+#.###.##.#..#...##.#.##.##..###.#.#.#..#.....#..##..#...#.#####.#.#.#.........#.#####.#..#####...#.#
+#..#.#...#####.#.##.##.#..##..###.##.#...##..#.##.#..#.###.#.##.#.#..##.###.###..#.#..#..#...##.##.#
+#...##.###..#.#...##.##...##..#..#.#.##.#.#..####..#####...##.##.####...#.###.#.##...##...#.##.##.##
+#.##..###..###.#...#.....#...##...#..##.##.#..##...###.#.....#.##.......#####.#####....#.###.#######
+..#...##.#..####...###..#.##...#.##.#.....##..##...#.#..#.#.#.##.......#...#.###..#....##.######....
+###.#..###..##.#........##.#.#.#..#....##.#...#....#.###..##.##.##.###..####.#####.....##...#..#.##.
+.####.##.....##............##.#...##.###...#.##..########.#..###......##..##.##..##..#.###....#.##..
+##.##.##.#..#...########.####.####.#.#.###..#...#.#.###..##.#.#.####.#..#.#.....#..#..##.#..##.##...
+##.##.#..#.....##.#####..#........####.#.#.##....#..#..#....###....#.......#.###.##.##...#..###..###
+##...#..#...#.#...##.#..###..###....#.#.......#...##.....#...#..#.#..###.##.##..###..#.#########.##.
+.#######...##.#..##.#####.....#....###.####.#.#.#..##.#.#..##...##.##.#.###.#.#....###.##.#.###.#..#
+..##.##..##.##.#.#..#.#..#.##..####..###..#######..#..#.#.#...###...#.###.#...#.###.##....##..#.###.
+#.......#...#.##...#.#...##....#.#....##.#.###.#.#...#...#######...###.#.#.##....###.#.##.#...##.##.
+##.##.#..##....#.######..##...#.##.#...#.#.####..####.##...####.#.#.#.##.#....###..##.#######..#..#.
+.....##....#.##.##.#.##....#.#.##.##......####.##..##.#....#..#.##.###.#..#....##.#..#.#.#.#.##...#.
+.#.#..#...#..#..#.....#####...#####..##.#.##.#.#....##..##............#.##...######..#.###..#...#..#
+#.#####.##.#.#.....#...#..#.#.#....#....#..##.#..#..#....####.#...#.##.####.#.##.#...#.#.#.#..#...##

2021/20/test.txt

@@ -0,0 +1,7 @@
+..#.#..#####.#.#.#.###.##.....###.##.#..###.####..#####..#....#..#..##..###..######.###...####..#..#####..##..#.#####...##.#.#..#.##..#.#......#.###.######.###.####...#.##.##..#..#..#####.....#.#....###..#.##......#.....#..#..#..##..#...##.######.####.####.#.#...#.......#..#.#.#...####.##.#......#..#...##.#.##..#...##.#.##..###.#......#.#.......#.#.#.####.###.##...#.....####.#..#..#.##.#....##..#.####....##...##..#...#......#.#.......#.......##..####..#...#.#.#...##..#.#..###..#####........#..####......#..#
+
+#..#.
+#....
+##..#
+..#..
+..###