<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 permutationsGenerator(vector<int>& nums, vector<int>& currentCombo, unordered_set<int>& indicesInCombo, set<vector<int>>& permutationSet)
    {
        if((nums.size() == currentCombo.size()))
        {
            permutationSet.insert(currentCombo);
            return;
        }

        for(int i=0; i<nums.size(); i++)
        {
            if(indicesInCombo.count(i) == 0)
            {
                currentCombo.push_back(nums[i]);
                indicesInCombo.insert(i);

                permutationsGenerator(nums, currentCombo, indicesInCombo, permutationSet);

                currentCombo.pop_back();
                indicesInCombo.erase(i);
            }
        }
    }

    vector<vector<int>> permuteUnique(vector<int>& nums) 
    {
        int n = nums.size();
        set<vector<int>> permutations;
        vector<int> currentCombo = {};
        unordered_set<int> indicesInCombo = {};

        permutationsGenerator(nums, currentCombo, indicesInCombo, permutations);

        return vector<vector<int>> (permutations.begin(), permutations.end());
    }
};
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