Comments on: Building a Tree from an Ordered List http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/ fragmentary ideas ䷿ intellectual what-nots ䷷ and haskell programming ䷴ Mon, 16 Aug 2010 13:21:24 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: Module for grouping lists in Haskell | LAMBDAPHONE http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/comment-page-1/#comment-109 Module for grouping lists in Haskell | LAMBDAPHONE Fri, 14 Aug 2009 01:14:26 +0000 http://coder.bsimmons.name/blog/?p=15#comment-109 [...] is an example from a previous post to build a binary tree from an in-order list, which uses the above [...]

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[...] is an example from a previous post to build a binary tree from an in-order list, which uses the above [...]

]]> By: jberryman http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/comment-page-1/#comment-12 jberryman Fri, 03 Apr 2009 03:30:42 +0000 http://coder.bsimmons.name/blog/?p=15#comment-12 josh, I played with trying to come up with something like that for a good long time, but couldn't quite get it. Thanks! josh, I played with trying to come up with something like that for a good long time, but couldn’t quite get it. Thanks!

]]> By: josh http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/comment-page-1/#comment-8 josh Wed, 01 Apr 2009 23:33:07 +0000 http://coder.bsimmons.name/blog/?p=15#comment-8 I don't know if it's any better, but I certainly think this is more clever: divide xs = let (parts, rest) = unzip . zipWith splitAt (iterate (*2) 1) . takeWhile (not . null) $ xs:rest in parts I don’t know if it’s any better, but I certainly think this is more clever:

divide xs = let (parts, rest) = unzip . zipWith splitAt (iterate (*2) 1) . takeWhile (not . null) $ xs:rest in parts

]]> By: admin http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/comment-page-1/#comment-7 admin Wed, 01 Apr 2009 21:47:32 +0000 http://coder.bsimmons.name/blog/?p=15#comment-7 Brian, thanks! That paper looks very readable and interesting. I found it <a href="http://www.informatik.uni-bonn.de/~ralf/publications/WAAAPL99b.ps.gz" rel="nofollow">here</a>. Brian, thanks! That paper looks very readable and interesting. I found it here.

]]> By: Brian Hurt http://coder.bsimmons.name/blog/2009/03/building-a-tree-from-an-ordered-list/comment-page-1/#comment-6 Brian Hurt Wed, 01 Apr 2009 20:26:49 +0000 http://coder.bsimmons.name/blog/?p=15#comment-6 I'd recommend reading: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.2171 Gives a real nice algorithm for building balanced trees from sorted lists of elements in O(N). The paper is talking about red-black trees, but there is nothing in the algorithm that really depends upon the balancing mechanism being anything particular, I've implemented it for height and weight balanced trees as well, and for descending as well as ascending lists. I’d recommend reading:

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.2171

Gives a real nice algorithm for building balanced trees from sorted lists of elements in O(N). The paper is talking about red-black trees, but there is nothing in the algorithm that really depends upon the balancing mechanism being anything particular, I’ve implemented it for height and weight balanced trees as well, and for descending as well as ascending lists.

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