<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:
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        set<pair<int, vector<int>>> s;
        pair<int,vector<int>> p(0,{});
        s.insert(std::move(p));
        set<vector<int>> perms;
        set<pair<int, vector<int>>> snext;
        while(!s.empty()){
            for(auto &[vmap,v] : s){
                for(int i = 0; i < nums.size();i++){
                    if((vmap & (1 << i)))continue;
                    vector<int> p = v;
                    int pmap = vmap | (1 << i);
                    p.push_back(nums[i]);
                    if(pmap + 1 == (1 << nums.size())){
                        perms.insert(p);
                    }
                    else snext.insert({pmap, p});

                }
            }
            s = move(snext);
        }
        return vector(perms.begin(),perms.end());

    }
};
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