In the TODO instructions for prufer_encode(tree) , why is step 1 instructed to copy the adjacency sets of the dictionary?

Question

In the TODO instructions for  prufer_encode(tree) , why is step 1 instructed to copy the adjacency sets of the dictionary?

Accepted Answer

To prevent mutating and destroying the original input  tree  dictionary during leaf removals.

Answer

Because Python dictionaries cannot delete keys while iterating over them.

Answer

To convert the undirected graph into a directed binary tree.

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