module Exercise_7 where

import Data.List
import Data.Maybe
import Control.Monad

{-WETT-}
trancl xs = if null xs'' then nub $ filter (isMin xs) xs else trancl (xs++xs'')
        where xs' = fmap not (`elem` xs) `filter` 
                    [(x1 + y1,(fst x2, snd y2)) | (x1,x2) <- xs, (y1,y2) <- xs, snd x2 == fst y2]
              xs'' = nub $ filter (isMin xs) xs'
              isMin xs (a,b) = isNothing $ find (\(a',b') -> b == b' && a' < a) xs
{-TTEW-}

{-MCCOMMENT
 - This is (according to my checks) technically correct, but has terrible runtime
 - and space-complexity. It does use less tokens tho, so I'm including it.
 - To be completely honest, I had next to no time for the competition this week
 - and I am kinda hoping that neither solutions are competetive.
 - (Also I had atleast some fun with comp trying to use liftM2 or some Applicatives
 -  but that turned out to be worse token-wise :D)
trancl xs = nub $ min $ comp $ concat $ take (2* length xs) $ iterate comp xs
        where comp xs = [(x1 + y1,(fst x2, snd y2)) 
                          | (x1,x2) <- xs, (y1,y2) <- xs, snd x2 == fst y2]
              min xs = filter (\(a,b) -> isNothing $ find (\(a',b') -> b == b' && a' < a) xs) xs
-}