Submission #111844

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Source Code Expand

import Data.List
import Data.Char
import Data.Maybe
import Data.Tuple
import Control.Applicative
import Debug.Trace
import qualified Data.ByteString.Char8 as B

debug x = trace (show x) x
(|>) x f = f x; infixl 1 |>
(||>) mx f = mx >>= (return . f); infixl 1 ||>
ref = (!!)

readInt = fst.fromJust.B.readInt
toDigit n = chr (48 + n)

ls2tpl :: [Int] -> (Int, Int)
ls2tpl [x,y] = (x-1 , y-1)

rd [] a = a
rd (l:ls) a =
  rd ls ((l |> words |> map read |> ls2tpl) : a)

main = do
  ls <- getContents ||> lines
  [n, m] <- head ls |> words |> map read |> return :: IO [Int]
  g <- rd (take m $ drop 1 ls) [] |> return
  print $ greedy n g 0 []

  where
    greedy n g i ls
      | i == n = length ls
      | ok g (i:ls) = max (greedy n g (i+1) (i:ls)) (greedy n g (i+1) ls)
      | True   = greedy n g (i+1) ls

    ok g ls =
      all id [ (i,j) `elem` g | i <- ls , j <- ls, i < j ]

Submission Info

Judge Result