app/cses1092.hs

   1 main :: IO ()
   2 main = do
   3   line1 <- getLine
   4   let n = read line1
   5   let solution = solve n
   6   putStrLn $ showSolution solution
   7
   8 solve :: Int -> Maybe ([Int] , [Int])
   9 solve n
  10   | n `mod` 4 == 0 = Just (mconcat [[k, n - k + 1] | k <- [1, 3 .. (n `div` 2)]],
  11                            mconcat [[k, n - k + 1] | k <- [2, 4 .. (n `div` 2)]])
  12   | n `mod` 4 == 3 = Just (mconcat [[k, n - k] | k <- [1, 3 .. (n `div` 2)]],
  13                            n : (mconcat [[k, n - k] | k <- [2, 4 .. (n `div` 2)]]))
  14   | otherwise = Nothing
  15
  16 showSolution Nothing = "NO"
  17 showSolution (Just (ns, ms)) = "YES\n" ++ (showNums ns) ++ "\n" ++ (showNums ms)
  18   where showNums ks = (show $ length ks) ++ "\n" ++ (unwords $ map show ks)