how to suppress carefully a recursive tree

From: fj <>
Date: Tue, 22 Jan 2008 03:04:40 -0800 (PST)
Message-ID: <>

I know how to suppress a normal tree but I meet the following kind of situation :


    -> b1

-> b2 -> ...
-> b3 -> ...

    -> b2

-> b1 -> ...
-> b1 -> ...

    -> b3

-> b4


    -> b3 -> ...

A same node can be referenced at several places. Each node is associated to a storage count :

r1(0) b1(3) b2(2) b3(3) b4(1) r2(0)

In a normal tree without recursion (in the example above, recursion occurs because b1 contains b2 and vice versa), a node is destroyed when its count storage is equal to zero else its count storage is simply decremented.

What algorithm should be applied ? I want for instance to cleanup r1 but, of course, r2 must remain valid (=> b3 and b4 are not destroyed during the process and their storage count must be b3(1) b4(1)).

Notice that the deletion of of a tree must be possible even if the count storage of the root is not equal to zero :

   r1 -> b1 -> b2 -> r1 -> ... Received on Tue Jan 22 2008 - 12:04:40 CET

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