2024-12-04 17:15:59 +11:00
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{-# OPTIONS_GHC -Wno-x-partial #-}
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import Aoc
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2024-12-02 18:55:47 +11:00
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import Data.List ( sort, group )
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import Data.Maybe ( fromMaybe )
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parseFile :: [String] -> ([Int], [Int])
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parseFile lines = unzip [(a, b) | line <- lines, let [a, b] = map read $ words line]
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part1 :: ([Int], [Int]) -> Int
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part1 (list1, list2) = sum $ zipWith (curry (abs . uncurry (-))) (sort list1) (sort list2)
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part2 :: ([Int], [Int]) -> Int
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part2 (list1, list2) = sum $ map score list1
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where
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score n = n * fromMaybe 0 (lookup n count)
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count = map (\xs -> (head xs, length xs)) $ group $ sort list2
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main :: IO ()
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main = aocMain parseFile part1 part2
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