hackerrank RemoveDuplicates from linkedlist

RemoveDuplicates.java

/*
Node is defined as 
  class Node {
     int data;
     Node next;
  }
*/

Node RemoveDuplicates(Node head) {
  Node current = head;
    while (current != null) {
        Node next = current.next;
        if (next != null && next.data == current.data) {
            current.next = next.next;
        } else {
            current = current.next;
        }
    }
    return head;
}

Node RemoveDuplicatesUnsorted(Node head) {
  SortedSet<Integer> elements = new SortedSet<Integer>();
  Node current = head;
    while (current != null) {
        Node next = current.next;
        if (next != null && elements.contains(next.data)) {
            current.next = next.next;
        } else {
            elements.add(current.data);
            current = current.next;
        }
    }
    return head;
}