my solution

class Solution {
public:
    void fun (vector <int> &nums , int idx, vector < vector <int>> &res, vector <int> path, unordered_map <int, bool> &vis)
    {
        if (path.size() == nums.size())
        {
            res.push_back(path);
            return ;
        }

        for (int i = 0 ; i < nums.size(); i ++)
        {
            if (vis[nums[i]]) continue;
            path.push_back(nums[i]);
            vis[nums[i]] = true;
            fun(nums, i, res, path, vis);
            path.pop_back();
            vis[nums[i]] = false;
        }
    }
    vector<vector<int>> permute(vector<int>& nums) {

        vector < vector <int>> res;
        vector <int> path;
        unordered_map <int, bool> vis;
        fun (nums, 0, res, path, vis);

        return res;


    }
};