37 lines
1.1 KiB
Haskell
37 lines
1.1 KiB
Haskell
module Main where
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import Data.Functor
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import Data.Char
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import Data.Matrix hiding (trace)
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import Data.List
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parse :: String -> Matrix Int
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parse = fromLists . ((digitToInt <$>) <$>) . lines
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getAllDigit :: Int -> Matrix Int -> [(Int,Int)]
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getAllDigit c s = zip [1..] (toLists s) >>= \(y,l) -> zip [1..] l >>= \(x,c') ->
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if c == c' then pure (y,x) else mempty
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getAbove :: (Int,Int) -> Matrix Int -> [(Int,Int)]
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getAbove (y,x) s = let target = getElem y x s + 1 in
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filter ((Just target ==) . flip (uncurry safeGet) s) [(y-1,x),(y+1,x),(y,x-1),(y,x+1)]
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travel :: (Int,Int) -> Matrix Int -> [(Int,Int)]
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travel p s = let curr = uncurry getElem p s in
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if curr == 9 then [p] else getAbove p s >>= (`travel` s)
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travel' :: (Int,Int) -> Matrix Int -> Int
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travel' p s = let curr = uncurry getElem p s in
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if curr == 9 then 1 else sum $ getAbove p s <&> (`travel'` s)
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solve1 :: Matrix Int -> Int
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solve1 s = length $ nub . (`travel` s) =<< getAllDigit 0 s
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solve2 :: Matrix Int -> Int
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solve2 s = sum $ getAllDigit 0 s <&> (`travel'` s)
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main :: IO ()
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main = readFile "inputs/10" <&> parse >>= \i ->
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print (solve1 i) >>
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print (solve2 i)
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