<p>Given an integer array <code>nums</code> of <strong>unique</strong> elements, 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 = [1,2,3]
<strong>Output:</strong> [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]
</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>
	<li>All the numbers of&nbsp;<code>nums</code> are <strong>unique</strong>.</li>
</ul>

class Solution {
private:
    void getSubsets(set<vector<int>>& sets, int level)
    {
        if (level == 0)
        {
            sets.insert(vector<int>());
            return;
        }

        for (auto iset : sets)
        {
            if (iset.size() != level + 1)
                continue;

            for (int i = 0; i < iset.size(); ++i)
            {
                vector<int> cset;
                for (int k = 0; k < iset.size(); ++k)
                {
                    if (k == i)
                        continue;

                    cset.push_back(iset[k]);
                }

                sets.insert(cset);
            }
        }

        getSubsets(sets, level - 1);
    }

public:
    vector<vector<int>> subsets(vector<int>& nums) {
        set<vector<int>> subsets;
        subsets.insert(nums);
        getSubsets(subsets, nums.size() - 1);

        vector<vector<int>> result;
        for (auto it = subsets.begin(); it != subsets.end(); ++it)
            result.push_back(*it);
        return result;
    }
};
10000