<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 solve( set<vector<int>>&ans,int index,vector<int> nums){
        if(index>=nums.size()){
            ans.insert(nums);
        }
        for(int i=index;i<nums.size();i++){
            swap(nums[i],nums[index]);
            solve(ans,index+1,nums);
             swap(nums[i],nums[index]);
        }
    }
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        int index=0;
         set<vector<int>> ans;
        solve(ans,index,nums);
         vector<vector<int>>ans1;
         
        
         for (const auto& vec : ans) {
            ans1.push_back(vec);
         }
        
        return ans1;
    }
};
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