thmain

public class DeleteTree {
	// to delete a binary tree, we need to set all the node objects to null then
	// garbage collection will take care of rest of the things
	//do the post order traversal and set the node to null
	public static Node deleteTree(Node root) {
		if (root != null) {
			deleteTree(root.left);
			deleteTree(root.right);	
			System.out.println("Deleting Node:" + root.data);
			root=null;

thmain

public class TreeTraversals {
	public void inorderRecursive(Node root) {
		if (root != null) {
			inorderRecursive(root.left);
			System.out.print(root.data + " ");
			inorderRecursive(root.right);
		}
	}

thmain

import java.util.Stack;
public class InorderIretation {

	public void inorderRecursive(Node root) {
		if (root != null) {
			inorderRecursive(root.left);
			System.out.print(root.data + " ");
			inorderRecursive(root.right);
		}

thmain

import java.util.Stack;

public class PreOrderTree {
	public void preOrderRecursive(Node root) {
		if (root != null) {
			System.out.print(root.data + " ");
			preOrderRecursive(root.left);
			preOrderRecursive(root.right);
		}

thmain

import java.util.Stack;

public class PostorderTree {

	public void postOrderRecursive(Node root) {
		if (root != null) {
			postOrderRecursive(root.left);
			postOrderRecursive(root.right);
			System.out.print(root.data + " ");

thmain

public class TreeToSumTree {
	
	static Node newRoot;

	public int SumTree(Node root){
		if(root!=null){
			int left = SumTree(root.left);//take the left tree sum
			int right = SumTree(root.right);//take the right tree sum
			int retData = root.data+left+right; // return data left+right+root

thmain

public class LeftLeavesSum {

	// Do the inorder traversal
	// check if node if the left child and leaf node
	// if yes then add it to the sum
	public static int leftLeavesSum = 0;

	public static void leftSum(Node root, Node parent) {
		if (root != null) {

thmain

import java.util.Comparator;
import java.util.PriorityQueue;

public class MaxRevenueTickets {

	PriorityQueue<Integer> pq;

	// we will create a max heap
	public MaxRevenueTickets(int length) {
		pq = new PriorityQueue<>(length, new Comparator<Integer>() {

thmain

public class ReverseInGrps {

	public Node reveseGrps(Node head, int k){
		int x = k;
		Node head_next=null;
		Node h = head;
		Node head_prev = null;
		while(h!=null && x>0){
			head_next = h.next;

thmain

public class ReverseAlternateKNodes {
    public static void main(String[] args) throws java.lang.Exception {
        LinkedListT a = new LinkedListT();
        for (int i = 1; i <= 12; i++) {
            a.addAtEnd(i);
        }
        System.out.print("Original Link List 1 : ");
        a.display(a.head);
        int k = 2;
        System.out.println("\n Recursion with 2k nodes where k = " +k);