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import Data.Void
import Prelude hiding ( (||) )
import Text.Megaparsec
import Text.Megaparsec.Char
import qualified Text.Megaparsec.Char.Lexer as L
type Parser = Parsec Void String
data Equation = Equation Int [Int]
equation :: Parser Equation
equation = do
test <- L.decimal
string ": "
nums <- L.decimal `sepBy` char ' '
pure $ Equation test nums
input :: Parser [Equation]
input = equation `sepEndBy` char '\n'
-- good enough
(||) :: Int -> Int -> Int
(||) b a = read $ show a ++ show b
prune :: Int -> [Int] -> [Int]
prune t = filter (<= t)
combos :: Int -> [Int] -> [Int]
combos t (n : ns) =
foldl (\s v -> prune t $ ((v +) <$> s) ++ ((v *) <$> s)) [n] ns
combos2 :: Int -> [Int] -> [Int]
combos2 t (n : ns) = foldl
(\s v -> prune t $ ((v +) <$> s) ++ ((v *) <$> s) ++ ((v ||) <$> s))
[n]
ns
solve :: (Int -> [Int] -> [Int]) -> [Equation] -> Int
solve f es = sum [ test | (Equation test _, m) <- zip es matches, m ]
where matches = (\(Equation test nums) -> test `elem` f test nums) <$> es
main :: IO ()
main = do
f <- readFile "input"
case runParser (input <* eof) "" f of
Right p -> do
print $ solve combos p
print $ solve combos2 p
Left err -> print $ errorBundlePretty err
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