Comments on: Which Numbers Sum to Target

By: Santosh

Santosh — Wed, 11 Jan 2012 06:41:48 +0000

It is not giving accurate answer by Benzadeus as Recursion worked.

By: benzadeus

benzadeus — Mon, 07 Nov 2011 17:10:00 +0000

Using recursion, I created a code my own in portuguese-br version: http://www.ambienteoffice.com.br/officevba/atingir_meta_de_soma/

It is easy to follow the sample workbook, even if you don't know portuguese: http://www.ambienteoffice.com.br/officevba/atingir_meta_de_soma/exemplo.rar

By: 0alex0

0alex0 — Sun, 29 May 2011 17:05:00 +0000

Thanks a lot; I just needed this macro for a otherwise seemingly unsolvable problem.

Kind regards,
0alex0

By: PK

PK — Fri, 13 May 2011 06:32:00 +0000

FYI to future readers

In response to Camilla's post the number records that can be processed can be increased by changing the length of the variables.

i.e.

instead of:

Global stat(30) AS Integer
Global statb(30) AS Double
Global elems(30) As Double

use:

Global stat(60) AS Integer
Global statb(60) AS Double
Global elems(60) As Double

this will allow you to use up to 60 values in the equation.

NOTE: using this many values will SIGNIFICANTLY increase the time taken to calculate!

By: Camilla

Camilla — Thu, 02 Dec 2010 22:52:00 +0000

HELP PLEASE

I get an error when my list of numbers exceed 30. The list i’m trying to work from has 700 numbers in the list. Has anyone been sucessful using this with a large range?

The error i get is below:
elems(i) = Cells(i + 2, 2)

any help would be greatly appreciated!

thanks

By: dermotb

dermotb — Thu, 25 Nov 2010 07:25:00 +0000

I think I have a faster solution in cases where you want to limit the number of items in the total, or the total number of possible solutions. It uses a couple of computer chess tricks (like pre-storing a large number of combinations). For example, given a target figure, I can find
* 8 items out of 60 items, in 20 seconds
* 5 items out of 200 items, in under a minute

Obviously, it gets much slower for more items, or where there are many possible solutions, but it should be pretty effective for business solutions.

It can definitely be made more efficient, and it hasn't been independently checked, because I did it just for fun, so I haven't fine tuned it, but I'm happy to share it.

Write to me at dermot dot balson at gmail dot com if you'd like a copy

By: Martin

Martin — Fri, 12 Nov 2010 17:19:00 +0000

This is great & I have used it on some smaller ranges, however on bigger ranges the number of possible combinations is extremly large & can be very slow.

For example I may have 200 numbers, but the figure I am looking for is probably made up of a combination of just 5 or fewer of these. How can I get the code just to look at these smaller combinations?

This way I can do a quicker check & if nothing is found, re-run for 10 number combinations, 15 etc, until I find the result.

By: Rebecca

Rebecca — Tue, 19 Oct 2010 23:21:00 +0000

THANK YOU SO MUCH! This was an enormous time-saver for me.

By: David J

David J — Wed, 27 Jan 2010 16:48:00 +0000

Just downloaded Recursion1.zip and it works perfectly! It’s a little slow with 30 to 40 combinations but all told it’s a life saver. I don’t know about the rest of you but I will be using this when I reconcile my credit card deposits in QuickBooks Pro. For the last 2 years I’ve cussed QB for not having this built in. THANKS!

By: Joe B

Joe B — Fri, 15 Jan 2010 23:11:00 +0000

1000 points to you.
I was presented the problem,
tried to solve it myself,
realized it would be difficult to code, (for me, at least)
found the name of the problem,
searched google,
and found you had already created the solver for me!

I'm thrilled, Thanks.

~Joe