Find nth node from last in a linked list

Approach 1:

STEP 1:  Take 2 pointers, say ptrA and ptrB. initialize both pointers pointing at start node.

STEP 2:  Move ptrB to Nth node from start keeping ptrA at start node. 

STEP 3:  If Nth position is not available that is, if ptrB encounters NULL before reaching Nth position, then given Nth position is not available and is incorrect, so return -1.
                 
                 If Nth position is valid input, then place ptr2 at Nth position.

STEP 4:   Now, when both pointers are at N distance from each other, increment ptrA and ptrB one node at a time until ptrB encounters NULL.

STEP 5:   When ptrB reaches NULL, it means ptrA reached Nth position from last. So return node at position ptrA.

public int NthElementfromLastSecondApproach(int nodeFromLast){

           Node ptr1=this.head;

           Node ptr2=this.head;

           // Return -1 if position is -ve or head is null

           if(nodeFromLast<=0 || this.head==null){

            return -1;

        }

           /* Move ptr2 to the nth element. Then move both pointers one by one,

           once ptr2 points to null, ptr1 points to the nth element from last */

           for(int i=0;i<nodeFromLast;i++){

                if(ptr2== null)

                     return -1;

                ptr2=ptr2.getNextNode();

           } // Now ptr2 pointing to nth element

          

           // Moving both elements one by one...

           while(ptr2 !=null){

                ptr2=ptr2.getNextNode();

                ptr1=ptr1.getNextNode();

           }

           return ptr1.getData();

}

Approach 2:

STEP 1: Find length of the list using length()

STEP 2: To find nth node from last, nthNode=length – n+1

STEP 3:Simply iterate and find the nthNode position which is nth node from last.

     void NthElementFromLast(int n) {

           int length = length();

           int nthNode = length - n + 1;

           Node node = find(nthNode);

           System.out.println(node);

     }

     public Node find(int position) {

           Node current = this.head;

           int count = 1;

           while (count != position) {

                current = current.getNextNode();

                count++;

           }

           return current;

         }

Running the program from main()- LinkedList.java

public class LinkedList {

     static Node head;

     public static void main(String[] args) {

           LinkedList linkedList = new LinkedList();

           linkedList.add(10);

           linkedList.add(20);

           linkedList.add(30);

           linkedList.add(40);

           linkedList.add(50);

           linkedList.add(60);

           linkedList.add(70);

           System.out.println(linkedList);

           //Node reverLinkedList = linkedList.reverseLinkedList();

           linkedList.NthElementFromLast(6);

           System.out.println(linkedList.NthElementfromLastSecondApproach(6));  }

}

Output:

{10-->20-->30-->40-->50-->60-->70-->null}

20

20