User talk:Gaaijz: Difference between revisions
(→Jers) |
|||
Line 13: | Line 13: | ||
Two different approaches with Haskell for the zigzag task. |
Two different approaches with Haskell for the zigzag task. |
||
flist = map (:[]) |
flist = map (:[]) |
||
elist = |
elist = cycle [[]] |
||
revNrev True = cycle [reverse,id] |
|||
revNrev _ = cycle [id,reverse] |
|||
transpN True = id |
|||
transpN _ = transpose |
|||
zigzag m n = |
zigzag m n = transpose. map concat. transpose |
||
. uncurry ((.(map (liftM2 (++) (elist.( |
. uncurry ((.(map (liftM2 (++) ((`take`elist).(`subtract`n).length) flist))).(++) |
||
.(map (liftM2 (++) flist ((`take`elist).(`subtract`n).length)))) |
|||
$ splitAt k revcs |
$ splitAt k revcs |
||
where |
where |
||
Line 26: | Line 23: | ||
dl = min m n |
dl = min m n |
||
nd = abs (m-n) |
nd = abs (m-n) |
||
⚫ | |||
rev = m<n |
|||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
groupon f x y= f x == f y |
groupon f x y= f x == f y |
||
tab n = fst . until (null.snd) (\(xs,ys)-> (xs++[take n ys], drop n ys)) . (,) [] |
tab n = fst . until (null.snd) (\(xs,ys)-> (xs++[take n ys], drop n ys)) . (,) [] |
||
Line 39: | Line 34: | ||
where fdiag = map (map snd). groupBy (groupon fst).sortBy (comparing fst) |
where fdiag = map (map snd). groupBy (groupon fst).sortBy (comparing fst) |
||
$ zip (map sum $ sequence [[0..m-1],[0..n-1]] ) [0..] |
$ zip (map sum $ sequence [[0..m-1],[0..n-1]] ) [0..] |
||
*Main> sum.map sum $ zigzag 500 500 |
*Main> sum.map sum $ zigzag 500 500 |
||
1185103928 |
1185103928 |
Revision as of 08:08, 7 September 2008
welcome!
Welcome to Rosetta Code! If you have any questions, drop them in the appropriate talk page, and someone will get back to you. If you have a more general question, try Mwn3d's or my talk pages. --Short Circuit 04:10, 2 September 2008 (UTC)
Jers
Hey Arie. This is Dan Bron from the J forums. Tracy Harms is here too. It's good to have J representation on RosettaCode. I'm glad you posted a J solution to the Pyramid of Numbers, that was near the top of my to do list. Have you considered posting a task along the lines of your Rabbit Sequence?
Oh, by the way, I linkified your user page. I hope you don't mind. Go ahead and revert it if you like it better the other way.
DanBron 13:48, 2 September 2008 (UTC)
Zigzag
Two different approaches with Haskell for the zigzag task.
flist = map (:[]) elist = cycle [[]] 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 tab n = fst . until (null.snd) (\(xs,ys)-> (xs++[take n ys], drop n ys)) . (,) [] grade xs = map snd. sort $ zip xs [0..] zigzagJ m n = tab n. grade .concat $ zipWith id (cycle [reverse,id]) fdiag where fdiag = map (map snd). groupBy (groupon fst).sortBy (comparing fst) $ zip (map sum $ sequence [[0..m-1],[0..n-1]] ) [0..]
*Main> sum.map sum $ zigzag 500 500 1185103928 (0.69 secs, 103908376 bytes) *Main> sum.map sum $ zigzagJ 500 500 31249875000 (4.55 secs, 575802084 bytes)