Get Start Node Of Loop In LinkList DS

Get Start Node Of Loop In LinkList i.e while linked list have loop.

package linkelist.example;

// get Start Node Of Loop In LinkList i.e. while loop in linked list
public class getStartNodeOfLoopInLinkList {

 Node startNode;

 public static void main(String[] args) {

  getStartNodeOfLoopInLinkList g = new getStartNodeOfLoopInLinkList();

  Node n1 = new Node(10);
  Node n2 = new Node(20);
  Node n3 = new Node(30);
  Node n4 = new Node(40);
  Node n5 = new Node(50);
  Node n6 = new Node(60);
  Node n7 = new Node(70);
  Node n8 = new Node(80);

  g.startNode = n1;

  n1.setNext(n2);
  n2.setNext(n3);
  n3.setNext(n4);
  n4.setNext(n5);
  n5.setNext(n6);
  n6.setNext(n7);
  n7.setNext(n8);
  n8.setNext(n6);

  Node loopNode = g.getStartNodeOfLoopInLinklist(g.startNode);

  if (loopNode == null) {
   System.out.println("Loop not present");
  } else {
   System.out.println("Start node of Loop is :" + loopNode.getData());
  }
 }

 private Node getStartNodeOfLoopInLinklist(Node startNode) {
  Node slowPointer = startNode; // Initially slowPointer is at starting location.
  Node fastPointer = startNode; // Initially fastPointer is at starting location.

  // If fastPointer encounters NULL, it means there is no Loop in Linked list.
  while (fastPointer != null && fastPointer.getNext() != null) {
   slowPointer = slowPointer.getNext(); // slowPointer moving one node at at time
   fastPointer = fastPointer.getNext().getNext(); // fastPointer moving two nodes at at time

   // if slowPointer and fastPointer meets, it means linked list contains loop.
   if (slowPointer == fastPointer) {

    // After meet, moving slowPointer to start node of list.
    slowPointer = startNode;

    // Moving slowPointer and fastPointer one node at a time till the time they
    // meet at common point.
    while (slowPointer != fastPointer) {
     slowPointer = slowPointer.getNext();
     fastPointer = fastPointer.getNext();
    }
    // returning start node of loop.
    return slowPointer;
   }
  }
  // this condition will arise when there is no loop in list.
  return null;
 }

}

package linkelist.example;

public class Node {

 private int data;
 private Node next;

 public Node(int data) {
  this.data = data;
 }

 public int getData() {
  return data;
 }

 public void setData(int data) {
  this.data = data;
 }

 public Node getNext() {
  return next;
 }

 public void setNext(Node next) {
  this.next = next;
 }
}

Output:

Start node of Loop is :60