29 lines
756 B
Haskell
29 lines
756 B
Haskell
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import Data.List (scanl', tails, transpose)
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import Data.Function (on)
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import Data.Bool (bool)
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expandEmpty :: Int
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expandEmpty = 2
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sumDistances :: (Int, Int) -> [(Int, Int)] -> Int
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sumDistances (n, d) = sum . map sumDistance
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where
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sumDistance (n', d') = n' * n * (d' - d)
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genDistances :: [Int] -> [Int]
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genDistances = scanl' (flip $ (+) . bool 1 expandEmpty . (== 0)) 0
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solveDirection :: [String] -> Int
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solveDirection = sum
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. (zipWith sumDistances <*> tail . tails)
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. (zip <*> genDistances)
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. map countHashes
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where
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countHashes = length . filter (== '#')
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solveAll :: [String] -> Int
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solveAll = ((+) `on` solveDirection) <*> transpose
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main :: IO ()
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main = print . solveAll . lines =<< readFile "data.txt"
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