Find out Linked List is Palindrome or not ?

/**

 * Palindrome Linked List (Recursive)

 *

 * @author:http://javainterviewprograms.blogspot.in/

 *

 */

public class Palindrom_LinkedList_Recursive {

          static ListNode left=null;

         

          public static void main(String[] args) {

                  

                   Linked_list ll = new Linked_list();

                   ll.InsertAtEnd(10);

                   ll.InsertAtEnd(20);

                   ll.InsertAtEnd(30);

                   ll.InsertAtEnd(20);

                   ll.InsertAtEnd(10);

                  

                   System.out.println("Is Palindrome:"+IsPalindrome(ll.getStart()));

          }

          private static boolean IsPalindrome(ListNode head) 

       {

                  

                   left = head;

                  

                   return IsPalindromeUtil(head);

          }

          private static boolean IsPalindromeUtil(ListNode head) 

       {

                  

                   if(head == null) return true;

                  

                   boolean b = IsPalindromeUtil(head.getNext()) && (left.getData()                        == head.getData());

                  

                   left = left.getNext();

                  

                   return b;

          }

}

Output:

Is Palindrome:true

Find Height of a Tree

/**

 * Find Height of a Tree

 *

 * @author:http://javainterviewprograms.blogspot.in/

 *

 */

public class Height_Of_The_Tree {

          public static void main(String[] args) {

                   // Binary search tree

                   Binary_Tree tree = new Binary_Tree();

                   tree.addNode(50);

                   tree.addNode(40);

                   tree.addNode(60);

                   tree.addNode(30);

                   tree.addNode(45);

                   tree.addNode(55);

                   tree.addNode(54);

                   tree.addNode(20);

                   tree.addNode(10);

                   // root.PreOrderTraversal();

                   int height = HeightOfTree(tree.getRoot());

                   System.out.println("Height Of Tree:" + height);

                   // Level Order Traversal Without Stack

                   LevelOrderTraversal(tree.getRoot(), height);

          }

          public static void LevelOrderTraversal(BSTNode root, int height) 
        {

                   for (int i = 1; i <= height; i++) {

                             LevelOrderTraversalUtil(root, i, 1);

                             System.out.println();

                   }

          }

          private static void LevelOrderTraversalUtil(BSTNode root, int level, int i) 
       {

                   if (root == null)

                             return;

                   if (i == level) {

                             System.out.print(root.data + " ");

                             // System.out.print(" data:"+root.data +" "+" level:"+level);

                   }

                   i++;

                   LevelOrderTraversalUtil(root.left, level, i);

                   LevelOrderTraversalUtil(root.right, level, i);

          }

          public static int HeightOfTree(BSTNode root)
        {

                   if (root == null) {

                             return 0;

                   }

                   int letfHeight = HeightOfTree(root.left);

                   int rightHeight = HeightOfTree(root.right);

                   if (letfHeight > rightHeight)

                             return 1 + letfHeight;

                   else

                             return 1 + rightHeight;

          }

}

Output:

Height Of Tree:5

50

40 60

30 45 55

20 54

10

Example of Serialization/Deserialization

package com.test.yuvagen.basic;

/**
 * Implements Serializable
 *
 * @author:http://javainterviewprograms.blogspot.in/
 *
 */

import java.io.*;

class Demo implements Serializable

{

    public int a;

    public String b;

         

    // Default constructor

    public Demo(int a, String b)

    {

        this.a = a;

        this.b = b;

    }

}

class Test

{

    public static void main(String[] args)

    {  

        Demo object = new Demo(1, "saurabh");

        String filename = "file.ser";

        

        // Serialization

        try

        {  

            //Saving of object in a file

            FileOutputStream file = new FileOutputStream(filename);

            ObjectOutputStream out = new ObjectOutputStream(file);

            

            // Method for serialization of object

            out.writeObject(object);

            

            out.close();

            file.close();

            

            System.out.println("Object has been serialized");

        }

        

        catch(IOException ex)

        {

            System.out.println("IOException is caught");

        }

        Demo object1 = null;

        // Deserialization

        try

        {  

            // Reading the object from a file

            FileInputStream file = new FileInputStream(filename);

            ObjectInputStream in = new ObjectInputStream(file);

            

            // Method for deserialization of object

            object1 = (Demo)in.readObject();

            

            in.close();

            file.close();

            

            System.out.println("Object has been deserialized ");

            System.out.println("a = " + object1.a);

            System.out.println("b = " + object1.b);

        }

        

        catch(IOException ex)

        {

            System.out.println("IOException is caught");

        }

        

        catch(ClassNotFoundException ex)

        {

            System.out.println("ClassNotFoundException is caught");

        }

    }

}

Output :

Object has been serialized

Object has been deserialized

a = 1

b = saurabh

Find out missing number from a series ?

package com.test.yuvagen.basic;

/**
 * Find Out Missing Number from series
 *
 * @author:http://javainterviewprograms.blogspot.in/
 *
 */

//Find out the missing number from a series

public class FindMissingNumber {

          /*

           *  For a Arithmetic Series (1, 2 3 ....n) | a(n)=a(1)+d*(n-1) ,where d is

           * difference in terms // sum=(n/2)*(a(1)+a(n))

           */

         

          // Method to determine missing number

          void findNumber(int[] series) {

                   // Assuming only one Number is missing

                   int lengthOfSeries = series.length + 1;

                   int sumOfSeries = 0;

                   int totalSum = 0;

                   sumOfSeries = ((lengthOfSeries) * (series[0] + series[series.length - 1])) / 2;

                   System.out.println("sumOfSeries :" + sumOfSeries);

                   for (int i = 0; i < series.length; i++) {

                             totalSum = totalSum + series[i];

                   }

                   System.out.println("totalSum :" + totalSum);

                   int missingNumber = sumOfSeries - totalSum;

                   System.out.println("Missing Number :" + missingNumber);

          }

          public static void main(String args[]) {

                   // int series[] = { 1, 2, 3, 4, 5, 6, 8, 9, 10, 11 };

                   int series[] = { -3, 0, 3, 6, 9, 12, 18, 21, 24 };

                   FindMissingNumber FMN = new FindMissingNumber();

                   FMN.findNumber(series);

          }

}

Output :

sumOfSeries :105

totalSum :90

Missing Number :15