26 lines
705 B
Haskell
26 lines
705 B
Haskell
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module Main where
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main :: IO ()
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main = do
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raw <- readFile "day1.txt"
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let ls = map read $ lines raw :: [Integer]
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in do
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case (solveA ls) of
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Nothing -> error "no answer"
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(Just x) -> putStrLn $ "day1a: " ++ (show x)
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case (solveB ls) of
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Nothing -> error "no answer"
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(Just x) -> putStrLn $ "day1b: " ++ (show x)
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solveA :: [Integer] -> Maybe Integer
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solveA [] = Nothing
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solveA xs = Just $ (\(x,y) -> x * y) lsa
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where
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lsa = head [ (x,y) | x <- xs, y <- xs, x + y == 2020 ]
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solveB :: [Integer] -> Maybe Integer
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solveB [] = Nothing
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solveB xs = Just $ (\(x,y,z) -> x * y * z) lsb
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where
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lsb = head [ (x,y,z) | x <- xs, y <- xs, z <- xs, x + y + z == 2020 ]
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