Created
December 6, 2023 01:11
-
-
Save icub3d/96c7d1dc5779e3ebd7ce78ba9d073357 to your computer and use it in GitHub Desktop.
Advent of Code - Day 04 - Part 1 - Haskell
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import Data.Bits (shift) | |
import Data.List (foldl') | |
import Data.Map (Map) | |
import qualified Data.Map as Map | |
import Data.Set (Set) | |
import qualified Data.Set as Set | |
import qualified Text.Parsec as Parsec | |
data Card = Card | |
{ winners :: Set Int, | |
ours :: Set Int | |
} | |
deriving (Show) | |
parseCard :: Parsec.Parsec String () Card | |
parseCard = do | |
Parsec.string "Card" | |
Parsec.spaces | |
Parsec.many1 Parsec.digit | |
Parsec.char ':' | |
Parsec.spaces | |
winners <- parseInts | |
Parsec.spaces | |
Parsec.char '|' | |
Parsec.spaces | |
ours <- parseInts | |
return $ Card (Set.fromList winners) (Set.fromList ours) | |
parseInts :: Parsec.Parsec String () [Int] | |
parseInts = do | |
ints <- Parsec.many1 Parsec.digit `Parsec.endBy` Parsec.spaces | |
return $ map read ints | |
parseCards :: Parsec.Parsec String () [Card] | |
parseCards = Parsec.many1 parseCard | |
parser :: String -> [Card] | |
parser input = case Parsec.parse parseCards "" input of | |
Left e -> error $ show e | |
Right r -> r | |
p1 :: [Card] -> Int | |
p1 cards = sum $ map (points . matches) cards | |
where | |
matches (Card w o) = length $ Set.intersection w o | |
points x = if x == 0 then 0 else 1 `shift` (x - 1) | |
main :: IO () | |
main = do | |
input <- readFile "input" | |
let cards = parser input | |
putStrLn $ "p1: " ++ show (p1 cards) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment