public class Solution {

boolean used[];

int res[];

int num[];

HashSet<ArrayList<Integer>> resSet;

ArrayList<ArrayList<Integer>> reslist;

public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {

// Start typing your Java solution below

// DO NOT rite main() function

used = new boolean[num.length];

res = new int[num.length];

this.num = num;

reslist = new ArrayList<ArrayList<Integer>>();

resSet = new HashSet<ArrayList<Integer>>();

pu(0);

reslist.addAll(resSet);

return reslist;

}

public void pu(int x){

for(int i=0;i<num.length;i++){

if(used[i]==false){

used[i] = true;

res[x] = num[i];

if(x==num.length-1){

ArrayList<Integer> y = new ArrayList<Integer>();

for(int j=0;j<res.length;j++){

y.add(res[j]);

}

resSet.add(y);

}else{

pu(x+1);

}

used[i] = false;

}

}

}

}