42 lines
1.2 KiB
Haskell
42 lines
1.2 KiB
Haskell
module Puzzles.Day6 (puzzle) where
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import Pre
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puzzle :: Puzzle
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puzzle =
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Puzzle
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{ number = 6
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, parser = const do
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ints <- some ((Just <$> digit) <|> (single ' ' $> Nothing)) `sepEndBy1` newline
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ops <- ((single '*' $> Multiply) <|> (single '+' $> Add)) `sepEndBy` hspace1
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void newline
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pure (ops, ints)
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, parts =
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[ sum
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. uncurry (zipWith applyToList)
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. second (transpose . map (map (digitsToInt @Int . catMaybes) . filter notNull . splitOn [Nothing]))
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, sum
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. uncurry (zipWith applyToList)
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. second
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( map catMaybes
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. splitOn [Nothing]
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. map (\l -> if all isNothing l then Nothing else Just $ digitsToInt @Int $ catMaybes l)
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. transpose
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)
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]
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, extraTests = mempty
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}
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data Op = Add | Multiply
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deriving (Eq, Ord, Show, Enum, Bounded)
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apply :: Op -> Int -> Int -> Int
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apply = \case
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Add -> (+)
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Multiply -> (*)
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unit :: Op -> Int
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unit = \case
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Add -> 0
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Multiply -> 1
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applyToList :: Op -> [Int] -> Int
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applyToList op = foldl' (apply op) (unit op)
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