Merge two sorted Linked List

 Merge 2 Sorted LinkedList :

class MergeLinkedList
{
  static class Node
  {
    int data;
    Node next;
  }
  public static void main(String[] args) {
    Node head1 = new Node();
    Node head2=  new Node();
    Node head3=  new Node();
    head3=null;
    head1.data=0;
    head2.data=1;
    head1=insert(insert(insert(insert(insert(insert(head1,2),5),7),8),9),11);
    head2=insert(insert(insert(insert(insert(head2,2),6),8),11),13);
    while(true)
    {
      if(head1==null && head2==null)
      {
        break;
      }
      else if(head1==null)
      {
        head3=insert(head3,head2.data);
        head2=head2.next;
      }
      else if(head2==null)
      {
        head3=insert(head3,head1.data);
        head1=head1.next;
      }
      else if(head1.data<=head2.data)
      {
        head3=insert(head3,head1.data);
          head1=head1.next;
      }
      else{
        head3=insert(head3,head2.data);
          head2=head2.next;
      }
    }
    printList(head3);
  }

  public static Node insert(Node head, int data) {
   Node node = new Node();
   node.data = data;
   node.next = null;
      if(head==null)
      return node;
 Node currentNode= head;
 while(currentNode.next!=null)
 {
     currentNode=currentNode.next;
     }

   currentNode.next=node;
   return head;
  }

 /**
  * Print All Elements of Linked List
  *
  * @param      node  The node
  */
  public static void printList(Node node) {
   Node currentNode = node;
   while (currentNode != null) {
    System.out.println(currentNode.data);
    currentNode = currentNode.next;
   }

}
}

Delete Nth Node From Linked List

Delete Nth Node  From Linked List : 

class DeleteNthNode

{

  static class Node {

   int data;

   Node next;

  }

  /**

  @main Method

  **/

  public static void main(String[] args) {

  Node head = insert(insert(insert(insert(null, 1), 2), 3),4);

  head= delete(head,0);

  head= delete(head,2);

  printList(head);

  }

  /**

   * Delete Node At Nth Position of Linked List

   *

   * @param      head  The head

   *

   * @param      Nth Position

   * @return     return head of Linked List

   */

  public static Node delete(Node head,int pos) {

   if (head == null) {

    return head;

   }

   if(pos==0)

   {

     Node next = head.next;

     return next;

   }

   else{

     Node currentNode=head;

     while((pos-1)>0)

     {

       currentNode=currentNode.next;

       pos--;

     }

    Node next = currentNode.next.next;

    currentNode.next=next;

    return head;

   }

  }

  /**

   * Insert Node at End

   *

   * @param      head  The head node

   * @param      data  The data

   *

   * @return     { description_of_the_return_value }

   */

   public static Node insert(Node head, int data) {

    Node node = new Node();

    node.data = data;

    node.next = null;

       if(head==null)

       return node;

  Node currentNode= head;

  while(currentNode.next!=null)

  {

      currentNode=currentNode.next;

      }

    currentNode.next=node;

    return head;

   }

 /**

  * Print All Elements of Linked List

  *

  * @param      Head of Linked List

  */

  public static void printList(Node node) {

   Node currentNode = node;

   while (currentNode != null) {

    System.out.println(currentNode.data);

    currentNode = currentNode.next;

   }

  }

}

Detect and Remove Loop in a Linked List

Detect & Remove Loop  From Linked List :

class DetectAndRemoveLoop

{

  static class Node {

   int data;

   Node next;

  }

  public static void main(String[] args) {

    Node node1 = new Node();

     node1.data = 1;

     Node node2 = new Node();

     node2.data = 2;

     Node node3 = new Node();

     node3.data = 3;

     Node node4 = new Node();

      node4.data = 4;

      Node node5 = new Node();

      node5.data = 5;

      Node node6 = new Node();

      node6.data = 6;

      Node node7 = new Node();

      node7.data = 7;

     node1.next = node2;

     node2.next = node3;

     node3.next = node4;

     node4.next=node5;

     node5.next=node6;

     node6.next=node7;

     node7.next=node3;

    if (detectAndRemove(node1) == true)

    {  printList(node1);  }

    else

    {System.out.println("No Loop Found"); }

  }

public  static boolean detectAndRemove(Node head)

  {

    Node slow=head;

    Node fast=head.next;

    while(fast!=null && fast.next!=null)

    {

      if(slow==fast)

      {

        break;

      }

    slow=slow.next;

    fast=fast.next.next;

  }

    if(slow==fast)

    {  slow=head;

        while(fast.next!=slow)

        {

          slow=slow.next;

          fast=fast.next;

        }

        fast.next=null;

        System.out.println("Loop Removed");

        return true;

    }

    return false;

  }

  public static void printList(Node node) {

   Node currentNode = node;

   while (currentNode != null) {

    System.out.println(currentNode.data);

    currentNode = currentNode.next;

   }

}

}

Swap Nodes in the Linked List

Swap nodes in a linked list without swapping data :

 

class SwapNodes

{

  static class Node{

    int data;

    Node next;

  }

  public static void main(String[] args) {

    Node head = new Node();

     head.data = 1;

     Node node2 = new Node();

     node2.data = 2;

     Node node3 = new Node();

     node3.data = 3;

     Node node4 = new Node();

      node4.data = 4;

      Node node5 = new Node();

      node5.data = 5;

      Node node6 = new Node();

      node6.data = 6;

      Node node7 = new Node();

      node7.data = 7;

     head.next = node2;

     node2.next = node3;

     node3.next = node4;

     node4.next=node5;

     node5.next=node6;

     node6.next=node7;

     node7.next=null;

     head=swap(head,2,6);

     //head=swap(head,2,3);

     printList(head);

  }

public static Node  swap(Node head , int x , int y)

{

        if(x==y)

          return head;

        // Search for x (keep track of prevX and CurrX)

        Node prevX = null, currX = head;

        while (currX != null && currX.data != x)

        {

            prevX = currX;

            currX = currX.next;

        }

        // Search for y (keep track of prevY and currY)

       Node prevY = null, currY = head;

       while (currY != null && currY.data != y)

       {

           prevY = currY;

           currY = currY.next;

       }

       // If either x or y is not present, nothing to do

        if (currX == null || currY == null)

            return head;

            // If x is not head of linked list

            if (prevX != null)

                prevX.next = currY;

            else //make y the new head

                head = currY;

            // If y is not head of linked list

            if (prevY != null)

                prevY.next = currX;

            else // make x the new head

                head = currX;

            // Swap next pointers

            Node temp = currX.next;

            currX.next = currY.next;

            currY.next = temp;

            return head;

}

            /**

 * Print All Elements of Linked List

 *

 * @param      Head of Linked List

 */

 public static void printList(Node node) {

  Node currentNode = node;

  while (currentNode != null) {

   System.out.println(currentNode.data);

   currentNode = currentNode.next;

  }

}

}