57 lines
1.5 KiB
Haskell
57 lines
1.5 KiB
Haskell
{-# LANGUAGE ImportQualifiedPost #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE TypeApplications #-}
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module Day05 (parse, solveA, solveB) where
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import Control.Monad (foldM)
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import Control.Monad qualified as T
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import Data.List (tails)
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import Data.Maybe (fromMaybe)
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import Data.Text (Text)
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import Data.Text qualified as T
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parse :: Text -> [Text]
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parse = T.lines
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isVovel :: Char -> Bool
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isVovel c = elem @[] c "aeiou"
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isWrong :: String -> Bool
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isWrong cs = cs `elem` ["ab", "cd", "pq", "xy"]
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isNice :: Text -> Bool
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isNice = maybe False (check . snd) . foldM next ('_', (False, 0)) . T.unpack
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where
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check :: (Bool, Int) -> Bool
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check (double, vowels) = double && vowels >= 3
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next :: ((Char, (Bool, Int)) -> Char -> Maybe (Char, (Bool, Int)))
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next (prev, (double, vowels)) char =
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let double' = double || prev == char
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vowels' = if isVovel char then vowels + 1 else vowels
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in if isWrong [prev, char]
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then Nothing
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else Just (char, (double', vowels'))
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solveA :: [Text] -> Int
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solveA = length . filter isNice
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checkTriple :: Text -> Bool
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checkTriple text
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| T.length text > 2 = T.index text 0 == T.index text 2
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| otherwise = False
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checkPairs :: Text -> Bool
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checkPairs "" = False
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checkPairs text =
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let (cs, rest) = T.splitAt 2 text
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in cs `T.isInfixOf` rest
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isNiceB :: Text -> Bool
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isNiceB text =
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let parts = T.tails text
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in any checkTriple parts && any checkPairs parts
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solveB :: [Text] -> Int
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solveB = length . filter isNiceB
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