So, let's say that I have a tree structure where 0
is the parent of all other nodes
parents=: p:inv 1+i.10
and that I have some numbers associated with
the nodes of this tree
n=: ?.100+i.10
I can produce a tree-wise sum, for example:
connmat=:3 :'(e."0 1/ [:|:{&y^:a:)i.#y'
treesum=: +/ .* |:@connmat
parents,n,:n treesum parents
0 0 1 2 2 3 3 4 4 4
46 25 101 69 102 9 58 45 40 64
559 513 488 136 251 9 58 45 40 64
I can also find the tree-wise difference, for example:
treediff=: %. connmat
559 513 488 136 251 9 58 45 40 64 treediff parents
46 25 101 69 102 9 58 45 40 64
However, it seems that there ought to be faster
approaches for large trees (with hundreds or
thousands of nodes).
So, since some people like puzzles, can anyone
come up with faster implementations for treesum
and treediff, for large trees?
Thanks,
--
Raul
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
