Day 13

2023-12-13 14:26:33 +01:00
parent 2f36550ebe
commit 03c18bbe91
5 changed files with 116 additions and 0 deletions
--- a/day13/Commons.hs
+++ b/day13/Commons.hs
@@ -0,0 +1,69 @@
+module Commons where
+
+import GHC.IO.Handle (isEOF)
+import Data.Array (Array, bounds, listArray, (!))
+
+
+data Tile = Ash | Rock deriving (Eq, Show)
+type Pattern = Array (Int, Int) Tile
+
+
+parseLine :: String -> [Tile]
+parseLine [] = []
+parseLine ('.': t) = Ash: parseLine t
+parseLine ('#': t) = Rock: parseLine t
+
+parsePattern :: IO [[Tile]]
+parsePattern = do done <- isEOF
+                  if done
+                     then return []
+                     else do line <- getLine
+                             if null line
+                                then return []
+                                else do let parsedLine = parseLine line
+                                        otherLines <- parsePattern
+                                        return $ parsedLine: otherLines
+
+parsePatterns :: [[[Tile]]] -> IO [Pattern]
+parsePatterns otherPatterns = do done <- isEOF
+                                 if done
+                                    then return $ map (\ p -> listArray ((1, 1), (length p, length (p !! 1)))
+                                                              $ concat p) otherPatterns
+                                    else do pattern <- parsePattern
+                                            parsePatterns $ otherPatterns ++ [pattern]
+
+parse :: IO [Pattern]
+parse = parsePatterns []
+
+
+isLineReflected :: (Int, Int) -> (Int, Int) -> Pattern -> Bool
+isLineReflected (y1, x1) (y2, x2) p
+  | x1 < 1 || x2 > snd (snd $ bounds p) = True
+  | otherwise                           = p ! (y1, x1) == p ! (y2, x2) && isLineReflected (y1, x1 - 1) (y2, x2 + 1) p
+
+isVerticalReflection :: (Int, Int) -> Pattern -> Bool
+isVerticalReflection (y, x) p
+  | y <= fst (snd $ bounds p) = isLineReflected (y, x) (y, x + 1) p && isVerticalReflection (y + 1, x) p
+  | otherwise                = True
+
+isColReflected :: (Int, Int) -> (Int, Int) -> Pattern -> Bool
+isColReflected (y1, x1) (y2, x2) p
+  | y1 < 1 || y2 > fst (snd $ bounds p) = True
+  | otherwise                           = p ! (y1, x1) == p ! (y2, x2) && isColReflected (y1 - 1, x1) (y2 + 1, x2) p
+
+isHorizontalReflection :: (Int, Int) -> Pattern -> Bool
+isHorizontalReflection (y, x) p
+  | x <= snd (snd $ bounds p) = isColReflected (y, x) (y + 1, x) p && isHorizontalReflection (y, x + 1) p
+  | otherwise                = True
+
+getVerticalReflection :: Int -> Int -> Pattern -> Int
+getVerticalReflection x ignore p | x >= snd (snd $ bounds p)     = 0
+                                 | x == ignore                   = getVerticalReflection (x + 1) ignore p
+                                 | isVerticalReflection (1, x) p = x
+                                 | otherwise                     = getVerticalReflection (x + 1) ignore p
+
+getHorizontalReflection :: Int -> Int -> Pattern -> Int
+getHorizontalReflection y ignore p | y >= fst (snd $ bounds p)       = 0
+                                   | y == ignore                     = getHorizontalReflection (y + 1) ignore p
+                                   | isHorizontalReflection (y, 1) p = y
+                                   | otherwise                       = getHorizontalReflection (y + 1) ignore p