<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 permuteAll(vector<int> nums, set<vector<int>>& output, vector<int>& temp, int start, int length) {
        if (length == 0) {
            output.insert(temp);
            return;
        }
        else {
            for (int i = 0; i < length; i++) {
                temp.push_back(nums[i]);
                nums.erase(nums.begin()+i);
                permuteAll(nums, output, temp, i + 1, length - 1);
                nums.insert(nums.begin()+i, temp.back());
                temp.pop_back();
            }
        }
    }
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        set<vector<int>> output = {};
        vector<int> temp = {};
        permuteAll(nums, output, temp, 0, nums.size());
        vector<vector<int>> vc(output.begin(), output.end());
        return vc;
    }
};
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