[gecode-users] saving the way to one of the solution in a file

[Guido Tack]

Hi.

> I've finally decided to use gecode instead of gecode/J so that I could
> modify the existing classes dfs.icc, reco-stack.icc and search.hh  
> rather
> than implement the whole from nothing.

Ok, that will make it easier for us to help you debugging, too.

> I've managed to get the way to the solution found, that is the list of
> alternatives to follow. But I don't really understand how to  
> rebuild the
> stack.
>
> In my opinion, I have to push a new ReCoNode in the stack for each
> alternative.

Yes, in principle, that's what you have to do. However, each ReCoNode  
contains a counter _alt that stores the alternative this node  
currently represents. So if you commit to alternative 1, you'd have  
to push a ReCoNode with _alt = 1. You will have to change some  
interfaces there in order to be able to set _alt.

> [...]
> Once the stack is rebuild, I thought I could simply call the method
> next().

Yes, that should work.

> I don't get any error, but the program simply stops when j = 1 but I
> don't know why...

Do you mean when i=1? Or do you mean a different j?

I would guess that if the nodes don't have the correct alternative  
stored in them, this can already be a problem. Another problem is  
that you will need at least one copy somewhere on the stack. That's  
the second argument to rcs.push. If there is no copy, recomputation  
does not work. So your first call to push should look like this

rcs.push(cur, cur->clone());

I hope you'll get it working using these hints.

Cheers,
	Guido

-- 
Guido Tack
Programming Systems Lab, Saarland University, Germany
http://www.ps.uni-sb.de/~tack