<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 {
public:
    void per(vector<int> nums, int l, int r, set<vector<int>>&st) {
        if (l == r) {
            st.insert(nums);

            return;
        }

        else {

            for (int i = l; i <= r; i++) {
        
        
                swap(nums[i], nums[l]);

                per(nums, l + 1, r, st);

                 swap(nums[i], nums[l]);
            }
        }
    }
    vector<vector<int>> permuteUnique(vector<int>& nums) {
   set<vector<int>>st;
        vector<vector<int>> v;

        per(nums, 0, nums.size() - 1, st);


        for(auto x:st){
            v.push_back(x);
        }


        

        return v;
    }
};
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