-- Problem   Genetic Code-- Algorithm Constructive-- Runtime   O(n)-- Author    Walter Guttmann-- Date      12.03.2003main :: IO ()main =  do input <- readFile "genetic.in"     mapM_ (putStrLn . flip take thue) $ takeWhile (>0) $ map read $ words inputthue :: Stringthue = head $ dropWhile tooShort $ iterate (concat . map replace) "N"  where tooShort xs = length xs < 5000        replace 'N' = "OP"        replace 'O' = "ONP"        replace 'P' = "N"