68 lines
3.9 KiB
Haskell
68 lines
3.9 KiB
Haskell
module Commons where
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import GHC.IO.Handle (isEOF)
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import Data.Set (Set, insert, member)
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import Data.Array (Array, listArray, bounds, (!), (//), Ix (inRange))
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data Direction = North | East | South | West deriving (Ord, Eq, Show)
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data Tile = Empty | Mirror | AntiMirror | HSplitter | VSplitter deriving (Eq, Show)
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type Cavern = Array (Int, Int) Tile
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parseLine :: String -> [Tile]
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parseLine [] = []
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parseLine ('/': t) = Mirror: parseLine t
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parseLine ('\\': t) = AntiMirror: parseLine t
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parseLine ('-': t) = HSplitter: parseLine t
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parseLine ('|': t) = VSplitter: parseLine t
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parseLine ('.': t) = Empty: parseLine t
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parseCavern :: IO [[Tile]]
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parseCavern = do done <- isEOF
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if done
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then return []
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else do line <- getLine
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let cavernLine = parseLine line
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cavern <- parseCavern
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return (cavernLine: cavern)
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parse :: IO Cavern
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parse = do cavern <- parseCavern
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return (listArray ((1, 1), (length cavern, length $ head cavern)) $ concat cavern)
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lightBeam :: (Int, Int) -> Direction -> Set (Int, Int, Direction) -> Cavern -> Set (Int, Int, Direction)
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lightBeam (y, x) East en c
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| member (y, x, East) en = en
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| not (inRange (bounds c) (y, x + 1)) = insert (y, x, East) en
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| let t = c ! (y, x + 1) in t == Empty || t == HSplitter = lightBeam (y, x + 1) East (insert (y, x, East) en) c
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| c ! (y, x + 1) == Mirror = lightBeam (y, x + 1) North (insert (y, x, East) en) c
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| c ! (y, x + 1) == AntiMirror = lightBeam (y, x + 1) South (insert (y, x, East) en) c
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| c ! (y, x + 1) == VSplitter =
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let en2 = lightBeam (y, x + 1) North (insert (y, x, East) en) c in lightBeam (y, x + 1) South en2 c
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lightBeam (y, x) West en c
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| member (y, x, West) en = en
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| not (inRange (bounds c) (y, x - 1)) = insert (y, x, West) en
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| let t = c ! (y, x - 1) in t == Empty || t == HSplitter = lightBeam (y, x - 1) West (insert (y, x, West) en) c
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| c ! (y, x - 1) == Mirror = lightBeam (y, x - 1) South (insert (y, x, West) en) c
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| c ! (y, x - 1) == AntiMirror = lightBeam (y, x - 1) North (insert (y, x, West) en) c
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| c ! (y, x - 1) == VSplitter =
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let en2 = lightBeam (y, x - 1) North (insert (y, x, West) en) c in lightBeam (y, x - 1) South en2 c
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lightBeam (y, x) South en c
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| member (y, x, South) en = en
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| not (inRange (bounds c) (y + 1, x)) = insert (y, x, South) en
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| let t = c ! (y + 1, x) in t == Empty || t == VSplitter = lightBeam (y + 1, x) South (insert (y, x, South) en) c
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| c ! (y + 1, x) == Mirror = lightBeam (y + 1, x) West (insert (y, x, South) en) c
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| c ! (y + 1, x) == AntiMirror = lightBeam (y + 1, x) East (insert (y, x, South) en) c
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| c ! (y + 1, x) == HSplitter =
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let en2 = lightBeam (y + 1, x) West (insert (y, x, South) en) c in lightBeam (y + 1, x) East en2 c
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lightBeam (y, x) North en c
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| member (y, x, North) en = en
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| not (inRange (bounds c) (y - 1, x)) = insert (y, x, North) en
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| let t = c ! (y - 1, x) in t == Empty || t == VSplitter = lightBeam (y - 1, x) North (insert (y, x, North) en) c
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| c ! (y - 1, x) == Mirror = lightBeam (y - 1, x) East (insert (y, x, North) en) c
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| c ! (y - 1, x) == AntiMirror = lightBeam (y - 1, x) West (insert (y, x, North) en) c
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| c ! (y - 1, x) == HSplitter =
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let en2 = lightBeam (y - 1, x) West (insert (y, x, North) en) c in lightBeam (y - 1, x) East en2 c
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