class Solution {
public:
    vector<int> path;
    vector<bool> st;
    vector<vector<int>> ans;

    vector<vector<int>> permute(vector<int>& nums) {
        path = vector<int>(nums.size());
        st = vector<bool>(nums.size());
        dfs(nums, 0);
        return ans;
    }

    void dfs(vector<int>& nums, int u)
    {
        if(u==nums.size())
        {
            ans.push_back(path);
            return;
        }
        for(int i=0;i<nums.size();i++)
        {
            if(!st[i])
            {
                path[u]=nums[i];
                st[i]=true;
                dfs(nums, u+1);
                st[i]=false;
            }
        }
    }
};