Main.hs

module Main (main) where

import           Control.Applicative
import qualified Data.Foldable as F
import           Data.Hashable (Hashable)
import qualified Data.HashSet as HS
import           Linear (V3(..))
import           System.Environment (getArgs)

type Forest = V3 Int

meals :: [Forest]
meals = [ V3 (-1) (-1)   1
        , V3 (-1)   1  (-1)
        , V3   1  (-1) (-1)
        ]

rmDups :: (Eq a, Hashable a) => [a] -> [a]
rmDups = go HS.empty
  where go _ []     = []
        go s (x:xs) = if x `HS.member` s then go s xs
                                         else x : go (HS.insert x s) xs

solve :: [Forest] -> [Forest]
solve fs = if null sol then solve fs' else sol
  where fs' = rmDups $ fs >>= \f -> filter (F.all (>= 0)) $ map (f +) meals
        sol = filter ((>= 2) . length . filter (== 0) . F.toList) fs'

main :: IO ()
main = do
    [g, w, l] <- map read <$> getArgs
    mapM_ print $ solve [V3 g w l]