24 lines
678 B
Haskell
24 lines
678 B
Haskell
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import Aoc
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import Data.List
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parseFile :: [String] -> [Char]
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parseFile = single
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move :: (Int, Int) -> Char -> (Int, Int)
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move (x, y) 'v' = (x, y - 1)
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move (x, y) '^' = (x, y + 1)
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move (x, y) '<' = (x - 1, y)
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move (x, y) '>' = (x + 1, y)
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visited :: [Char] -> [(Int, Int)]
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visited = uncurry (:) . foldl (\(loc, locs) c -> (move loc c, loc:locs)) ((0, 0), [])
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part1 :: [Char] -> Int
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part1 = length . nub . visited
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part2 :: [Char] -> Int
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part2 = length . nub . uncurry (++) . both visited . split
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where split cs = foldr (\(c, i) (evens, odds) -> if even i then (c:evens, odds) else (evens, c:odds)) ([], []) (zip cs [0..])
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main :: IO ()
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main = aocMain parseFile part1 part2
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