genetic.hs.txt

Ulm大学2003-2004年竞赛题

-- Problem   Genetic Code
-- Algorithm Constructive
-- Runtime   O(n)
-- Author    Walter Guttmann
-- Date      12.03.2003

main :: IO ()
main =
  do input <- readFile "genetic.in"
     mapM_ (putStrLn . flip take thue) $ takeWhile (>0) $ map read $ words input

thue :: String
thue = head $ dropWhile tooShort $ iterate (concat . map replace) "N"
  where tooShort xs = length xs < 5000
        replace 'N' = "OP"
        replace 'O' = "ONP"
        replace 'P' = "N"