import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param num int整型一维数组 
     * @return int整型ArrayList<ArrayList<>>
     */
    
    public void recursion(ArrayList<ArrayList<Integer>> res,ArrayList<Integer> temp,int[] num,boolean[] vis){

        if(temp.size() == num.length){
            res.add(new ArrayList<Integer>(temp));
        }
        for(int i = 0; i < num.length; i++){
            if(vis[i]) 
                continue;
            if(i > 0 && num[i-1] == num[i] && !vis[i-1])
                continue;

            vis[i] = true;
            temp.add(num[i]);
            recursion(res,temp,num,vis);
            vis[i] = false;
            temp.remove(temp.size()-1);
        }


    }




    public ArrayList<ArrayList<Integer>> permuteUnique (int[] num) {
        // write code here
        

        ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> temp = new ArrayList<Integer>();

        Arrays.sort(num);
        boolean[] vis = new boolean[num.length];
        Arrays.fill(vis,false);

        
        recursion(res,temp,num,vis);

        return res;
    }
}