C++ 代码

class Solution {
private:
    int n;
    vector<vector<int>> res;
    vector<int> flag = vector<int> (8, 0);
    vector<int> index = vector<int> (8, 0);
public:
    void dfs(int step, vector<int>& nums)
    {
        if(step == n)
        {
            vector<int> tmp;
            for(int i = 0; i < n; i++) tmp.push_back(nums[index[i]]);
            res.push_back(tmp);
            return;
        }
        for(int i = 0; i < n; i++)
        {
            if(!flag[i])
            {
                flag[i] = 1;
                index[step] = i;
                dfs(step + 1, nums);
                flag[i] = 0;
            }
        }
    }
    vector<vector<int>> permute(vector<int>& nums) {
        n = nums.size(); // index 1 - n的全排列
        dfs(0,  nums);
        return res;
    }
};