duplicatequeue.java

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class duplicatequeue {
 
 public static void doublequeue(Queue<Integer> q){
 int size = q.size();

 for(int i = 0;i<size;i++){
 int x = q.poll();

 q.add(x);
 q.add(x);
 }
 }

 public static void main(String[] args)
 {
 Scanner sc = new Scanner(System.in);

 int n = sc.nextInt();

 Queue<Integer> q = new LinkedList<>();

 for(int i = 0; i < n; i++)
 {
 q.offer(sc.nextInt());
 }

 doublequeue(q);

 while(!q.isEmpty())
 {
 System.out.print(q.poll() + " ");
 }
 }
}