40 lines
840 B
Haskell
40 lines
840 B
Haskell
module Aoc.Y2020.D01
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( day
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) where
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import Control.Monad
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import Aoc.Day
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import Aoc.Parse
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findPair :: [Integer] -> (Integer, Integer)
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findPair l = head $ do
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a <- l
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b <- l
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guard $ a + b == 2020
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pure (a, b)
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findTriple :: [Integer] -> (Integer, Integer, Integer)
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findTriple l = head $ do
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a <- l
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b <- l
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c <- l
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guard $ a + b + c == 2020
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pure (a, b, c)
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parser :: Parser [Integer]
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parser = manyLines decimal
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solver :: [Integer] -> IO ()
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solver values = do
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putStrLn ">> Part 1"
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let (x1, x2) = findPair values
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putStrLn $ show x1 ++ " * " ++ show x2 ++ " = " ++ show (x1 * x2)
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putStrLn ""
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putStrLn ">> Part 2"
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let (y1, y2, y3) = findTriple values
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putStrLn $ show y1 ++ " * " ++ show y2 ++ " * " ++ show y3 ++ " = " ++ show (y1 * y2 * y3)
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day :: Day
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day = dayParse parser solver
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