M=:?.100+i.3000
P=:p:inv 1+i.3000
Not a big deal, but:
separating structure (connection matrix) from calculating sums:
cm=:connmat P
10 ts 'M +/"1@:*"1 cm'
0.0573582 55296
10 ts 'M +/ .*|:cm'
0.1671801 16795264
trees1=:+/"1@:*"1 connmat
n(trees1-:treesum)parents
1
M(trees1-:treesum)P
1
Raul Miller schreef:
> 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,
>
>
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