24 lines
589 B
Haskell
24 lines
589 B
Haskell
main :: IO ()
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main = do
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input <- map (concat . repeat) . lines <$> readFile "input"
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print $ day3 input ((3,1),0)
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let slopes = [((1,1),0),((3,1),0),((5,1),0),((7,1),0),((1,2),0)]
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print $ product $ map (day3 input) slopes
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type Slope = ((Int, Int), Int)
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day3 :: [String] -> Slope -> Int
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day3 input slope = a
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where
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(_, a) = day3rec (input, 0) slope
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day3rec :: ([String], Int) -> Slope -> ([String], Int)
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day3rec (t:ts, acc) ((x, y), l) =
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day3rec
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( drop y (t : ts)
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, if t !! (l * x) == '.'
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then acc
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else succ acc)
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((x, y), succ l)
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day3rec x _ = x
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