In the TODO instructions for prufer_encode(tree), why is step 1 instructed to copy the adjacency sets of the dictionary?
For values = [10, 20, 30, 40, 50, 60], what list does array_preorder(values) return?
(Format answer exactly as a Python list string, e.g. [1, 2, 3])
In prufer_decode(sequence), after processing all elements in the input sequence list, what final step completes the graph reconstruction?