<p>Given a collection of numbers, <code>nums</code>,&nbsp;that might contain duplicates, return <em>all possible unique permutations <strong>in any order</strong>.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,1,2]
<strong>Output:</strong>
[[1,1,2],
 [1,2,1],
 [2,1,1]]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,2,3]
<strong>Output:</strong> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 8</code></li>
	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
</ul>

class Solution {
     set<vector<int>>v;
    void dfs(vector<int>nums,int i){
        if(i == nums.size()-1){
           v.insert(nums);
            return;}
        dfs(nums, i+1);
        for(int j=i+1;j<nums.size();j++){
            
            swap(nums[i],nums[j]);
            dfs(nums,i+1);
            swap(nums[i],nums[j]);
        }
    }
public:
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        dfs(nums,0);
        vector<vector<int>> ans;
        for(auto i:v)ans.push_back(i);
        return ans;
    }
};
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