/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		permute(1,2,3);
	}
 
    public static List<List<Integer>> permute(int... nums) {
       List<List<Integer>> list = new ArrayList<>();
       // Arrays.sort(nums); // not necessary
       backtrack(list, new ArrayList<>(), nums, "");
       return list;
    }
 
    private static void backtrack(List<List<Integer>> list, List<Integer> tempList, int [] nums, String spaces){
       if(tempList.size() == nums.length){
          list.add(new ArrayList<>(tempList));
       } else{
          for(int i = 0; i < nums.length; i++){ 
             if(tempList.contains(nums[i])) 
                 continue;
             System.out.println(spaces + "Adding: "+nums[i]);
             tempList.add(nums[i]);
             backtrack(list, tempList, nums, spaces + "  ");
             System.out.println(spaces + "Removing: "+nums[i]);
             tempList.remove(tempList.size() - 1);
          }
       }
    } 
}

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