Limit recursion with one deepest loop and assign exact id to all elements

Question

It is necessary to order the elements from the mixed order. Ordering is done using the recursion method. Two conditions must be met that while are not implemented in the code:

Answer 1

Only how to choose the longest one chain?

Consider the following much simplified example.

IMPORTANT
In this example it is assumed that a parent object can have at most one child object. This allows us to begin the recursion with ancestor objects (objects that do not have a parent) and work downwards. Otherwise we would have to create a separate chain for every leaf object (an object that does not have any child objects) and recurse upwards from there.

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