Algorithm ideas

From: NotAsDumbAsILook (toyota_trekker_at_yahoo.com)
Date: 02/19/04 

Date: 18 Feb 2004 17:09:09 -0800

Hello all!

I'm updating some engineering software at work (moving it off of the
mainframe, which entails translating the old COBOL to a Java
application), and trying to come up with a good idea for a new
algorithm. I'm an engineer who does programming on the side. I'm
well-versed, but not nearly as knowledgable as someone who pounds out
code 40+ hours per week. I've come up with a few ideas (other than
just copying the old algorithm, which is accurate, but slow and
clunky). But, I'd really like to use an optimal algorithm. I want it
to be as fast as possible. So, I'm wondering if anyone can point me to
any books or articles that discuss algorithms that would fit my needs.
 I can't say exactly what the program is or does because of company
proprietary information issues, but I'll make an example as best I
can.

Imagine you have a bunch of data that is in a tree structure. You have
a top-level folder that contains other folders, and documents. Those
sub-folders can, in turn, contain other sub-folders and documents. The
structure goes down several layers deep, until a folder only contains
documents. Each document has a number written on it. You have to add
up all of the documents to get the value of the folder that contains
those documents. In a folder that contains documents and sub-folders
it's value is the sum of the documents plus the sum of the values of
the sub-folders. This addition rolls all the way up to the top-level
folder until it is given a value.

One requirement is that I need to be able to look at any folder in the
structure and see what it's value is (the sum of everything below it).
That means I can't just parse through the tree and add up all of the
documents. This has to be a recursive thing that gives me the
subtotals at each folder.

Speed is most important (next to accuracy). A user who is looking at
the top-most folder in this structure will be dealing with 15,000+
documents plus the sub-folders, so something on the order of 20,000
items that the algorithm would have to crank through when updates to
the documents are made. The user's computers really get a good
workout.

So, if anyone has seen anything resembling this in a book or
periodical, or if you just have an idea, let me know.

Thanks,
Kevin

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