Find 'n' th last element in a singly Linked list

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• Posted: 7 years ago

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LinkedListNode findNthNodeFromEnd(LinkedListNode head, int n){

      /* Empty linked list */
      if (head == null || n  <  1) 
          return null;

      /* Initialize two pointers at the beginning of the list */
      LinkedListNode pointer1 = head;
      LinkedListNode pointer2 = head;

     /* Increment pointer2 by (n-1) locations */
     for (int j = 0; j  <  n - 1; ++j){
         /* When the length of the list is less than n */
         if (pointer2 == null) 
             return null;
         /* Increment 1 location */
         pointer2 = pointer2.next;
     }

     /* Increment both the pointers until pointer2 reaches the last node */
     while (pointer2.next != null){
         pointer1 = pointer1.next;
         pointer2 = pointer2.next;
     }

     /* pointer1 is now the nth node from the end - return it */
     return pointer1;
 }