Data Structures and Algorithms
with Object-Oriented Design Patterns in C++ 
The purpose of the IsEmpty accessor function is to determine
whether a given N-ary tree is the empty tree.
The implementation of this function is given in Program 
.
In this implementation,
the key pointer is zero if the tree is the empty tree.
Therefore, IsEmpty returns true if when the key
member variable is zero.
Clearly this is a constant time, O(1), operation.
Program: NaryTree Class Member Function Definitions
Copyright © 1997 by Bruno R. Preiss, P.Eng. All rights reserved.