Question

public Iterator preOrderlterator() The method returns an iterator that performs the preorder traversal on the tree. The iterator must be dynamic in the following sense: if after the iterator is created, and the tree changes in some part that has not been processed by the iterator yet, then the iterator "will see" these changes and output the values in the updated tree when reaching that part of the tree. However, if you change the nodes that have already been processed, then it wil have no effect on the iterator. Be careful, do not change the nodes that are currently being processed, as this may have unexpected effects This means you cannot simply create the list with the preorder traversal of the tree in the constructor of the iterator. It will not work in the dynamic sense. You will probably need to implement the iterator in a new class. Please declare the class in the package binarytree. Make sure to submit the java file implementing the iterator.

Answer 1

To implement an iterator that performs preorder traversal on a binary tree, you need to create a new class that implements the Iterator interface and defines the necessary methods for iterating through the tree in a preorder manner. One possible implementation is to use a stack to keep track of the nodes during the traversal.

Step-by-step explanation:

In order to implement an iterator that performs preorder traversal on a binary tree, you will need to create a new class in the 'binarytree' package. This class should implement the 'Iterator' interface and define the necessary methods for iterating through the tree in a preorder manner. The iterator should be able to handle dynamic changes to the tree, so any updates made after it is created should be reflected in the iteration results.

One possible implementation of this iterator class could be to use a stack to keep track of the nodes during the traversal. Here is a basic structure for the class:

package binarytree;import java.util.Iterator;public class PreOrderIterator implements Iterator{ private Node currentNode; private Stack> stack; public PreOrderIterator(Node root) { // initialize the current node and stack } public boolean hasNext() { // check if there are still nodes to be traversed } public T next() { // move to the next node in the iteration and return its value }}

By using this iterator class, you can then call the 'preOrderlterator()' method on your tree object to get an iterator that performs preorder traversal on the tree. Any changes made to the tree after creating the iterator will be reflected in the iteration results.