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Diffstat (limited to '4/2.hs')
-rw-r--r-- | 4/2.hs | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/4/2.hs b/4/2.hs new file mode 100644 index 0000000..b728231 --- /dev/null +++ b/4/2.hs @@ -0,0 +1,24 @@ +import Prelude +import Text.Parsec.String (Parser) +import Text.Parsec +import System.Environment +import Control.Monad +import qualified Data.Set as S +import Data.Maybe + +type Card = (S.Set Int, S.Set Int) + +numbers = S.fromList <$> ((many1 space) *> sepEndBy (read <$> many1 digit) (many1 space)) + +card :: Parser Card +card = string "Card" *> spaces *> many1 digit *> char ':' *> liftM2 (,) (numbers <* (char '|')) numbers + +cards = many1 card + +solution :: [Card] -> Int +solution = sum . map (+1) . foldr f [] where + f (picked,winning) ws = w : ws where + m = length $ S.intersection picked winning + w = m + sum (take m ws) + +main = liftM2 (>>=) readFile (((print . solution . either (error.show) id) .) . parse cards) =<< head <$> getArgs \ No newline at end of file |