[Choco-users] Backtrackable data structures

[Malcolm R. <mal...@cs...>]

Hi,

I'm trying to write a constraint which represents the partitioning of  
a set into a collection of disjoint subsets. To make sure that the  
subsets are disjoint, it is useful to keep track of how many subsets  
have each element in their kernel or envelope. It is more efficient  
to store this information and update it as we are notified of  
additions and removals, rather than to scan all the sets on every  
pass. I have written code which uses a HashMap for this purpose, but  
it just occured to me that this will not work with backtracking. Is  
there an appropriate alternative structure which will respond to  
backtracking appropriately?

Thanks,
Malcolm

--
"If there is one thing worse than the modern weakening of major morals
    it is the modern strengthening of minor morals.
Thus it is considered more withering to accuse a man
    of bad taste than of bad ethics."    -- G.K.Chesterton, On Lying  
in Bed