Question

Write a (void) method to traverse a binary tree in Breadth-First order, where you start from the root, print the node values of its children, (left and then right) (these are at level 1), then print all node values at level 2 from left to right, and then level 3 etc. For the example binary tree below, you should get the result A, B, E, C, F, D, G, H. Notice that this type of traversal is not the same as any of the three methods we discussed in class (inOrder, preOrder, and postOrder). Hint: No recursion needed.

Answer 1

import java.util.LinkedList;

public class BinaryTree {

TreeNode root = null;

TreeNode current, parent;

private int size = 0, counter = 0;

public int getSize() {

return this.size;

}

public boolean insert(char el) {

current = root;

if (current == null) {

root = new TreeNode(el);

} else {

parent = null;

current = root;

while (current != null) {

if (el < current.element) {

parent = current;

current = current.left;

} else if (el > current.element) {

parent = current;

current = current.right;

} else {

return false;

}

}

if (el < parent.element) {

parent.left = new TreeNode(el);

}

if (el > parent.element) {

parent.right = new TreeNode(el);

}

}

this.size++;

return true;

}

public void levelOrderTraversal(TreeNode node) {

if (node == null)

return ;

LinkedList<TreeNode> queue = new LinkedList<TreeNode>();

queue.add(node);

while (!queue.isEmpty()) {

TreeNode tempNode = queue.poll();

System.out.println(tempNode.element + " ");

if (tempNode.left != null)

queue.add(tempNode.left);

if (tempNode.right != null)

queue.add(tempNode.right);

}

}

public void levelOrderTraversal() {

levelOrderTraversal(root);

}

}

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// start Driver class

public class TreeDriver {

public static void main(String[] args) {

BinaryTree tree = new BinaryTree();

tree.insert('A');

tree.insert('B');

tree.insert('E');

tree.insert('C');

tree.insert('F');

tree.insert('D');

tree.insert('G');

tree.insert('H');

System.out.println("Breadth first Traversal: ");

tree.levelOrderTraversal();

}

}

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// start TreeNode class

public class TreeNode {

char element;

TreeNode left;

TreeNode right;

public TreeNode(char el) {

this.element = el;

}

}

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SEE OUTPUT

PLEASE COMMENT if there is any concern.

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