<p>Given an integer array <code>nums</code> that may contain duplicates, return <em>all possible</em> <span data-keyword="subset"><em>subsets</em></span><em> (the power set)</em>.</p>

<p>The solution set <strong>must not</strong> contain duplicate subsets. Return the solution in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> nums = [1,2,2]
<strong>Output:</strong> [[],[1],[1,2],[1,2,2],[2],[2,2]]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> nums = [0]
<strong>Output:</strong> [[],[0]]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10</code></li>
	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
</ul>

class Solution {
public:
     void solve(vector<int> &nums, vector<int> output, vector<vector<int>> &ans, int index) {
        if (index == nums.size()) {
            ans.push_back(output);
            return;
        }
       
        output.push_back(nums[index]);
        solve(nums, output, ans, index + 1);
        
        
        output.pop_back();
        solve(nums, output, ans, index + 1);
    }

    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        vector<int> output;
        vector<vector<int>> ans;
    
        sort(nums.begin(), nums.end());

        solve(nums, output, ans, 0);

        set<vector<int>> set;

        for (int i = 0; i < ans.size(); i++) {
            set.insert(ans[i]);
        }
  
        ans.clear();

        for (const auto& subset : set) {
            ans.push_back(subset);
        }

        return ans;
    }
};
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