advent06/src/advent06.hs

   1 -- import Debug.Trace
   2
   3 import Data.Text (Text)
   4 import qualified Data.Text as T
   5 import qualified Data.Text.IO as TIO
   6
   7 import Data.Attoparsec.Text
   8 -- import Data.Attoparsec.Combinator
   9
  10 import qualified Data.Set as S
  11
  12 main :: IO ()
  13 main =
  14   do  text <- TIO.readFile "data/advent06.txt"
  15       let groups = successfulParse text
  16       -- print groups
  17       print $ part1 groups
  18       print $ part2 groups
  19
  20 part1 groups = sum $ map (S.size . S.unions) groups
  21 part2 groups = sum $ map (S.size . intersections) groups
  22
  23 intersections :: Ord a => [S.Set a] -> S.Set a
  24 intersections group = foldl S.intersection (head group) group
  25
  26 -- -- Parse the input file
  27
  28 blankLines = skipMany1 endOfLine
  29
  30 personP = S.fromList <$> many1 letter
  31 groupP = sepBy1 personP endOfLine
  32
  33 groupsP = sepBy groupP blankLines
  34
  35 successfulParse :: Text -> [[S.Set Char]]
  36 successfulParse input =
  37   case parseOnly groupsP input of
  38     Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
  39     Right groups -> groups