17 lines
649 B
Haskell
17 lines
649 B
Haskell
import Data.List (isPrefixOf)
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import Data.List.Split (split, splitOn, startsWith)
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import Data.Char (isDigit)
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import Text.Regex.TDFA (getAllTextMatches, (=~))
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sumMul :: [String] -> Int
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sumMul xs = let vals = map (splitOn "," . filter (`elem` "0123456789,")) xs
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in sum $ map (product . map read) vals
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filterDonts :: [String] -> String
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filterDonts = concat . filter (not . isPrefixOf "don't()") . concatMap (split (startsWith "do()"))
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main = do
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contents <- split (startsWith "don't()") <$> readFile "day3.txt"
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let mults = getAllTextMatches (filterDonts contents =~ "mul\\([0-9]+,[0-9]+\\)") :: [String]
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print $ sumMul mults
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