adventofcode/2023/app/Day2.hs
2023-12-04 00:00:50 +01:00

97 lines
2.7 KiB
Haskell

module Day2 where
import System.IO
import ParseLib.Abstract
import Prelude hiding ((<$), ($>), (<*), (*>), sequence)
import Data.Maybe
import Data.List
import Foreign (toBool)
main :: IO ()
main = do
handle <- openFile "app/Day2-input.txt" ReadMode
input <- hGetContents handle
let games = map (fst . head . parse parseGame . fst . head . parse lexer) (lines input)
cubes = map maxColors games
possible = filter isPossible cubes
total = sum (map fst possible)
putStr "Part 1: "
print total
let power = sum $ map totalPower cubes
putStr "Part 2: "
print power
where
isPossible :: (Int, [Color]) -> Bool
isPossible (_, cs) =
fromMaybe (Red 0) (find isRed cs) <= Red 12
&& fromMaybe (Green 0) (find isGreen cs) <= Green 13
&& fromMaybe (Blue 0) (find isBlue cs) <= Blue 14
totalPower :: (Int, [Color]) -> Int
totalPower (_, cs) =
value (fromMaybe (Red 1) (find isRed cs)) *
value (fromMaybe (Green 1) (find isGreen cs)) *
value (fromMaybe (Blue 1) (find isBlue cs))
data Token = TGame Int
| TRed Int
| TBlue Int
| TGreen Int
| TSep
deriving (Show, Eq)
isTGame TGame{} = True
isTGame _ = False
isTRed TRed{} = True
isTRed _ = False
isTBlue TBlue{} = True
isTBlue _ = False
isTGreen TGreen{} = True
isTGreen _ = False
lexer :: Parser Char [Token]
lexer = greedy parseToken
parseToken :: Parser Char Token
parseToken = TGame <$ token "Game " <*> natural <* token ": "
<|> TRed <$> natural <* token " red" <* greedy (token ", ")
<|> TBlue <$> natural <* token " blue" <* greedy (token ", ")
<|> TGreen <$> natural <* token " green" <* greedy (token ", ")
<|> TSep <$ token "; " <* greedy (token ", ")
data Game = Game Int [[Color]] deriving Show
data Color = Red Int | Green Int | Blue Int deriving (Show, Eq, Ord)
value (Red i) = i
value (Green i) = i
value (Blue i) = i
isRed Red{} = True
isRed _ = False
isBlue Blue{} = True
isBlue _ = False
isGreen Green{} = True
isGreen _ = False
colors (Game _ cs) = cs
parseGame :: Parser Token Game
parseGame = (\(TGame g) cs -> Game g cs) <$> satisfy isTGame <*> listOf (many parseColor) (symbol TSep)
parseColor :: Parser Token Color
parseColor = (\(TRed i) -> Red i) <$> satisfy isTRed
<|> (\(TGreen i) -> Green i) <$> satisfy isTGreen
<|> (\(TBlue i) -> Blue i) <$> satisfy isTBlue
maxColors :: Game -> (Int, [Color])
maxColors (Game i cs) = (i, [maximum red, maximum green, maximum blue])
where
red = mapMaybe (find isRed) cs
green = mapMaybe (find isGreen) cs
blue = mapMaybe (find isBlue) cs