<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 helper(vector<int> nums, int i, vector<int> & current, vector<vector<int>> &result) {
        int n = nums.size();
        if(i==n) {
            result.push_back(current);
            return;
        }

        current.push_back(nums[i]);
        helper(nums, i+1, current, result);
        current.pop_back();
        while(i+1<n && nums[i] == nums[i+1]) {
            i++;
        }
        helper(nums, i+1, current, result);
    }
    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        vector<vector<int>> result;
        vector<int> current;
        sort(nums.begin(), nums.end());
        helper(nums, 0, current, result);
        return result;
    }
};
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