<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{set<vector<int>>s;
void S(vector<int>ss,multiset<int>SS){
if(SS.empty()){s.insert(ss);return;}
for(auto v:set<int>(SS.begin(),SS.end())){
    vector<int>sss=ss;sss.push_back(v);
    multiset<int>SSS=SS;SSS.erase(SSS.find(v));
    S(sss,SSS);}}
public:vector<vector<int>>permuteUnique(vector<int>&nums){
s.clear();S({},multiset<int>(nums.begin(),nums.end()));
return vector<vector<int>>(s.begin(),s.end());}};
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