class Solution {
public:
    vector<vector<int>> permutation(vector<int>& nums) {
        sort(nums.begin(),nums.end());  //先把输入的数字进行排序

        vector<vector<int> > res; //二维vector
        do res.push_back(nums);   // 将nums中的元素加到res后面
        while (next_permutation(nums.begin(),nums.end())); //这个函数走到最大序列后会返回false

        return res;
    }
};