Submission #139553

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Source Code Expand

import qualified Data.ByteString.Char8 as B
import Control.Applicative ((<$>))
import Data.Maybe (fromJust)

main = do
  [n,m] <- map (read :: String -> Int) . words <$> getLine
  xs <- concat . map (\[x,y] -> [(x,y),(y,x)]) . map (map (fst . fromJust . B.readInt)) . map B.words . B.lines <$> B.getContents
  print $ solve n xs

perm :: Int -> [[Int]]
perm 0 = [[]]
perm n = map (n:) zs ++ zs
  where zs = perm (n-1)

mkpair :: [Int] -> [(Int,Int)]
mkpair [] = []
mkpair (x:xs) = map (\y->(x,y)) xs ++ zs
  where zs = mkpair xs

solve :: Int -> [(Int,Int)] -> Int
solve n xs = maximum $ [x | ys <- perm n, isAllin xs (mkpair ys), let x = length ys]
  where isAllin ss [] = True
        isAllin ss (t:ts) = elem t ss && isAllin ss ts

Submission Info

Judge Result