<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:
    void ans(vector<int> &v, int ind, vector<int> &nums, set<vector<int>> &st) {
        if (ind >= nums.size()) {
            vector<int> arr(nums.size());
            for (int i = 0; i < nums.size(); i++) {
                arr[i] = nums[v[i]];
            }
            st.insert(arr);
            return;
        }

        for (int i = 0; i < v.size(); i++) {
            if (v[i] == -1) {
                v[i] = ind;
                ans(v, ind + 1, nums, st);
                v[i] = -1;
            }
        }
    }

    vector<vector<int>> permuteUnique(vector<int>& nums) {
        set<vector<int>> st;
        vector<int> v(nums.size(), -1);
        ans(v, 0, nums, st);
        vector<vector<int>> asd;
        for (auto it : st) {
            asd.push_back(it);
        }
        return asd;
    }
};

23644