How to use matlab container.map?

Hi all, I have the following problem. I have a potentially large number of objects. The objects are the nodes of a tree. Each branch stems from a node and can generate a node with further branches. There are several trees and the thing is that several trees may have some of their nodes that are identical. I would like to flag each node in such a way that all identical nodes in different trees (and branches) have the same reference. I would like to put a reference only on the nodes that are re-used.

Here is a lousy example with its solution:

 tree(1).nodes={a,b,c}; tree(2).nodes= {b,c,d,e};

 tree(1).refs={'','r1','r2'}; tree(2).refs= {'r1','r2','',''};

In the first stage, when constructing tree(1), the references are empty since none of the nodes (in this simple example) is re-used. But then when constructing tree(2), realizing that b and c where already computed, they are flagged.

I was told I should be looking for hash tables or hash maps and I found out that the equivalent in matlab is the class container.map. But I do not understand how to use it or at least in a way that solves my problem.

Can someone help? Thanks,

Pat.