27 lines
1.0 KiB
Haskell
27 lines
1.0 KiB
Haskell
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import Data.List
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main :: IO ()
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main = do
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input <- map (map (subtract 48.fromEnum)) <$> lines <$> readFile "input"
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print $ sum $ day8 (fromEnum . any (/=0)) walkLine1 input
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print $ maximum $ day8 product walkLine2 input
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walkLine2 :: Int -> [Int] -> Int
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walkLine2 x (y:ys) = 1 + if y < x then walkLine2 x ys else 0
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walkLine2 _ [] = 0
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walkLine1 :: Int -> [Int] -> Int
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walkLine1 x (y:ys) = if y < x then walkLine1 x ys else 0
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walkLine1 _ [] = 1
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checkPoint :: (Int -> [Int] -> Int) -> (Int,Int) -> [[Int]] -> [Int]
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checkPoint f (x,y) field = [f num line | line <- [lineX1,lineX2,lineY1,lineY2]]
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where num = field !! y !! x
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lineX1 = drop (x+1) $ field !! y
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lineX2 = reverse $ take x $ field !! y
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lineY1 = drop (y+1) $ (transpose field) !! x
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lineY2 = reverse $ take y $ (transpose field) !! x
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day8 :: ([Int] -> Int) -> (Int -> [Int] -> Int) -> [[Int]] -> [Int]
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day8 f1 f2 field = [f1 $ checkPoint f2 (x,y) field | x<-[0..(subtract 1 $ length $ head field)], y<-[0..(subtract 1 $ length field)]]
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