Data Structures and Algorithms
with Object-Oriented Design Patterns in Java 
Program 
defines the three methods
for manipulating the subtrees of an N-ary tree.
The getSubtree method takes as its argument
an int, i, which must be between 0 and N-1.
It returns the 
subtree of the given tree.
Note that this operation is only defined for a non-empty N-ary tree.
Given that the tree is not empty,
the running time is O(1).
The attachSubtree method takes two arguments.
The first is an integer i between 0 and N-1.
The second is an NaryTree instance.
The purpose of this method is to make the N-ary tree specified
by the second argument become the 
subtree of the given tree.
It is only possible to attach a subtree to a non-empty node and
it is only possible to attach a subtree
in a place occupied by an empty subtree.
If none of the exceptions are thrown,
the running time of this method is simply O(1).
The detachSubtree method takes a single argument i
which is an integer between 0 and N-1.
This method removes the subtree from a given N-ary
tree and returns that subtree.
Of course, it is only possible to remove a subtree from a non-empty tree.
Since every non-empty node must have N subtrees,
when a subtree is removed it is replaced by an empty tree.
Clearly, the running time is O(1) if we assume that no exceptions are thrown.
Copyright © 1998 by Bruno R. Preiss, P.Eng. All rights reserved.
