49 lines
1.3 KiB
Haskell
49 lines
1.3 KiB
Haskell
import Data.List (scanl, tails, transpose, zip4, zipWith4)
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import Data.Text (Text)
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import qualified Data.Text as T (lines, unpack)
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import Lib (readFile')
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-- new approach was hinted by an anon but I cannot quite get it right
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-- a fun approach, not necessarily the fastest (or cleanest (or smartest))
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main :: IO ()
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main = do
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input <- map T.unpack . T.lines <$> readFile' "day8.in"
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putStr "Q1: "
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print $ q1 input
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putStr "Q2: "
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print $ q2 input
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layer :: [[Char]] -> (a -> a -> a) -> ([[Char]] -> [[a]]) -> [[a]]
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layer input f f' =
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zipWith4 ( zipWith4 (\w x y z -> f w . f x $ f y z) )
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(f' e)
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(map reverse $ f' w)
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(transpose $ f' n)
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(reverse . transpose $ f' s)
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where
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(e, w, n, s) =
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( input,
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map reverse input,
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transpose input,
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transpose $ reverse input
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) -- (east, west, north, south]
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q1 :: [[Char]] -> Int
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q1 input = length . filter not . concat $ layer input (&&) q1'
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where
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q1' :: [[Char]] -> [[Bool]]
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q1' = map (\x -> zipWith (<=) x $ scanl max minBound x)
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q2 :: [[Char]] -> Int
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q2 input = maximum . concat $ layer input (*) q2'
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where
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q2' :: [[Char]] -> [[Int]]
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q2' =
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map
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( \a ->
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[ let l = length (takeWhile (< x) xs) in (+ l) . fromEnum $ length xs /= l
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| (x : xs) <- tails a
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]
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)
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