edge.hs.txt

Ulm大学2003-2004年竞赛题

-- Problem   Edge
-- Algorithm Straight-Forward
-- Runtime   O(n)
-- Author    Walter Guttmann
-- Date      05.01.2003

import Complex;
import Monad;

type Comp = Complex Double

main :: IO ()
main = readFile "edge.in" >>= mapM_ solve . words

solve :: String -> IO ()
solve s =
  do putStrLn "300 420 moveto"
     putStrLn "310 420 lineto"
     foldM turn (310:+420,10:+0) s
     putStrLn "stroke"
     putStrLn "showpage"

turn :: (Comp,Comp) -> Char -> IO (Comp,Comp)
turn (pos,d) c =
  let print (x:+y) = show (round x) ++ " " ++ show (round y) ++ " lineto"
      d' = rot d c
      pos' = pos + d'
  in putStrLn (print pos') >> return (pos',d')

rot :: Comp -> Char -> Comp
rot d 'A' = d * (0:+(-1))
rot d 'V' = d * (0:+1)