How to extend breadth first Search for Binary Tree to any kind of Tree??

Question

Dear Friends,
I am thinking a problem, How to extend breadth first Search for Binary Tree to any kind of Tree?? ie each node has more than 2 leaves such as 1, 2,3,4 or any,
I have following code to successfully apply for breadth first Search in Binary Tree as follows,
package a.border;
import java.util.ArrayList;
import java.util.LinkedList;
public class Tree
    int root;
    Tree left;
    Tree right;
    static ArrayList<Integer> list = new ArrayList<Integer>();
    static ArrayList<Tree> treeList = new ArrayList<Tree>();
    private static LinkedList<Tree> queue = new LinkedList<Tree>();
     * @param root root value
     * @param left left node
     * @param right right node
    public Tree(int root, Tree left, Tree right)
        this.root = root;
        this.left = left;
        this.right = right;
    /** Creates a new instance of Tree
     * You really should know what this does...
     * @param root
    public Tree(int root)
        this.root = root;
        this.left = null;
        this.right = null;
     * Simply runs a basic left then right traversal.
    public void basicTraversal()
        //Check if we can go left
        if (left != null)
            left.basicTraversal();
        //Add the root
        list.add(root);
        //Check if we can go right
        if (right != null)
            right.basicTraversal();
    public ArrayList<Integer> getBreadthTraversal(ArrayList<Integer> list)
        //Add the root to the arraylist, we know it is always the first entry.
        list.add(root);
        //Basically we add the first set of nodes into the queue for
        //traversing.
        //Query if left exists
        if (left != null)
            //Then add the node into the tree for traversing later
            queue.add(left);
        //Same for right
        if (right != null)
            queue.add(right);
        //Then we call the traverse method to do the rest of the work
        return traverse(list);
    private ArrayList<Integer> traverse(ArrayList<Integer> list)
        //Keep traversing until we run out of people
        while (!queue.isEmpty())
            Tree p = queue.remove();
            //Check if it has any subnodes
            if (p.left != null)
                //Add the subnode to the back of the queue
                queue.add(p.left);
            //Same for left
            if (p.right != null)
                //Same here, no queue jumping!
                queue.add(p.right);
            //Append to the ArrayList
            list.add(p.root);
        //And return
        return list;
     * Makes a tree and runs some operations
     * @param args
    public static void main(String[] args)
         *                             4
         *          t =           2       6
         *                      1   3    5   7
        Tree leaf6 = new Tree(1);
        Tree leaf7 = new Tree(3);
        Tree leaf8 = new Tree(5);
        Tree leaf9 = new Tree(7);
        Tree t4 = new Tree(2, leaf6, leaf7);
        Tree t5 = new Tree(6, leaf8, leaf9);
        Tree t = new Tree(4, t4, t5);
        t.basicTraversal();
        System.out.println("Here is basicTraversal ="+list.toString());
        list.clear();
        t.getBreadthTraversal(list);
        System.out.println("getBreadthTraversal= " +list.toString());
        list.clear();
    }Can Guru help how to update to any kind of tree??
here this code is for the tree like:
         *                             4
         *          t =           2       6
         *                      1   3    5   7
         */But i hope the new code can handle tree like:
         *                             4
         *                           /   | \
         *                          /     |   \
         *          t =            2     8   6
         *                        / |  \    |    /| \
         *                      1 11  3 9   5 10  7
         */Thanks

Answer 1

sunnymanman wrote:
Dear Friends,
I am thinking a problem, How to extend breadth first Search for Binary Tree to any kind of Tree?? ...The answer is interfaces.
What do all trees have in common? And what do all nodes in trees have in common?
At least these things:
interface Tree<T> {
    Node<T> getRoot();
interface Node<T> {
    T getData();
    List<Node<T>> getChildren();
}Now write concrete classes implementing these interfaces. Let's start with a binary tree (nodes should have comparable items) and an n-tree:
class BinaryTree<T extends Comparable<T>> implements Tree<T> {
    protected BTNode<T> root;
    public Node<T> getRoot() {
        return root;
class BTNode<T> implements Node<T> {
    private T data;
    private Node<T> left, right;
    public List<Node<T>> getChildren() {
        List<Node<T>> children = new ArrayList<Node<T>>();
        children.add(left);
        children.add(right);
        return children;
    public T getData() {
        return data;
class NTree<T> implements Tree<T> {
    private NTNode<T> root;
    public Node<T> getRoot() {
        return root;
class NTNode<T> implements Node<T> {
    private T data;
    private List<Node<T>> children;
    public List<Node<T>> getChildren() {
        return children;
    public T getData() {
        return data;
}Now with these classes, you can wite a more generic traversal class. Of course, every traversal class (breath first, depth first) will also have something in common: they return a "path" of nodes (if the 'goal' node/data is found). So, you can write an interface like this:
interface Traverser<T> {
    List<Node<T>> traverse(T goal, Tree<T> tree);
}And finally write an implementation for it:
class BreathFirst<T> implements Traverser<T> {
    public List<Node<T>> traverse(T goal, Tree<T> tree) {
        Node<T> start = tree.getRoot();
        List<Node<T>> children = start.getChildren();
        // your algorithm here
        return null; // return your traversal
}... which can be used to traverse any tree! Here's a small demo of how to use it:
public class Test {
    public static void main(String[] args) {
        Tree<Integer> binTree = new BinaryTree<Integer>();
        // populate your binTree
        Tree<Integer> nTree = new NTree<Integer>();
        // populate your nTree
        Traverser<Integer> bfTraverser = new BreathFirst<Integer>();
        // Look for integer 6 in binTree
        System.out.println("bTree bfTraversal -> "+bfTraverser.traverse(6, binTree));
        // Look for integer 6 in nTree
        System.out.println("bTree bfTraversal -> "+bfTraverser.traverse(6, nTree));
}Good luck!