User talk:Gaaijz: Difference between revisions

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 == Zigzag ==
 Two different approaches with Haskell for the zigzag task.
+ zigzag m n = take m .transp_wof $ zipWith id (cycle [reverse,id]) antiDiags where
- flist = map (:[])
+   mmn        = min m n
- elist = cycle [[]]
+   antiDiags  = unfoldr (\((c:cs),xs) -> if null xs then Nothing else Just (take c xs,(cs,drop c xs)))
+                ([1..mmn-1]++(replicate (succ.abs $ m-n) mmn)++[mmn-1,mmn-2..0], [0..m*n-1])
+   transp_wof = unfoldr (\xs -> if null xs then Nothing else Just $ next xs)
+   next xs    =  (,) (concatMap (take 1) ks) ((map (drop 1) $ drop 1 ks) ++ ts)
+        where (ks,ts) = splitAt n xs
- zigzag m n = transpose. map concat. transpose
-  . uncurry ((.(map (liftM2 (++) ((`take`elist).(`subtract`n).length) flist))).(++)
-              .(map (liftM2 (++) flist ((`take`elist).(`subtract`n).length))))
-  $ splitAt k revcs
-  where
-   k  =  truncate . sqrt . fromIntegral $ (m*n)
-   dl = min m n
-   nd = abs (m-n)
-   antiDiags = unfoldr (\((c:cs),xs) -> if null xs then Nothing else Just (take c xs,(cs,drop c xs)))
-               ([1..dl]++(replicate nd dl)++[dl-1,dl-2..0], [0..m*n-1])
-   revcs = zipWith id (cycle [id,reverse]) antiDiags
 :Slower version, almost complete emulation of the J-solution
  groupon f x y= f x == f y