content: import java.io.IOException;
  import java.util.Scanner;
  
  public class solution {
  
      static class SinglyLinkedListNode {
          public int data;
          public SinglyLinkedListNode next;
  
          public SinglyLinkedListNode(int nodeData) {
              this.data = nodeData;
              this.next = null;
          }
      }
  
      static class SinglyLinkedList {
          public SinglyLinkedListNode head;
          public SinglyLinkedListNode tail;
  
          public SinglyLinkedList() {
              this.head = null;
              this.tail = null;
          }
  
          public void insertNode(int nodeData) {
              SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);
              if (this.head == null) {
                  this.head = node;
              } else {
                  this.tail.next = node;
              }
              this.tail = node;
          }
      }
  
      //Member method to print the data of the nodes of singlyLinkedList
      public static void printSinglyLinkedList(SinglyLinkedListNode node) throws IOException {
          while (node != null) {
              System.out.print(node.data + " -> ");
              node = node.next;
          }
          System.out.println("NULL");
      }
  
      static SinglyLinkedListNode removeDuplicates(SinglyLinkedListNode head) {
          if (head == null) {
              return null;
          }
          //Create a temporary node to traverse through the linked list
          SinglyLinkedListNode n = head;
          //While next of current node is not null traverse through the linked list
          while (n.next != null) {
              //If data of current node is similar to data of next node
              if (n.data == n.next.data)
              {
                  //Point next of current node to next of next of current node
                  n.next = n.next.next;
              }
              //Move to the next node
              else {
                  n = n.next;
              }
          }
          //Finally return the head
          return head;
      }
  
      private static final Scanner scanner = new Scanner(System.in);
  
      public static void main(String[] args) throws IOException {
  
          int t = scanner.nextInt();
          for (int tItr = 0; tItr < t; tItr++) {
              SinglyLinkedList llist = new SinglyLinkedList();
              int llistCount = scanner.nextInt();
              for (int i = 0; i < llistCount; i++) {
                  int llistItem = scanner.nextInt();
                  llist.insertNode(llistItem);
              }
  
              SinglyLinkedListNode llist1 = removeDuplicates(llist.head);
              printSinglyLinkedList(llist1);
          }
          scanner.close();
      }
  }
  
  