100 doors: Difference between revisions

Content added Content deleted

Inline

@@ Line 781: / Line 781: @@
 '''unoptimized'''
 <lang haskell>data Door = Open | Closed deriving Show
+toggle Open   = Closed
+toggle Closed = Open
-toggle f []          = []
+pass k = zipWith ($) (cycle $ replicate k id ++ [toggle])
-toggle f (Open:xs)   = Closed : f xs
-toggle f (Closed:xs) = Open   : f xs
+run n = foldl (flip pass) (replicate n Closed) [0..n]</lang>
-pass k [] = []
-pass k xs = ys ++ toggle (pass k) zs where (ys,zs) = splitAt k xs
-run n = snd $ (!! n) $
-  iterate (\(k,xs) -> (k+1, pass k xs)) $ (0, replicate n Closed)</lang>
 '''optimized'''