题目：

代码(首刷看解析 2024年2月3日）：

class Solution {
private:vector<vector<int>> res;vector<int> path;
public:void backtracking(vector<int>& nums, int startIndex) {res.push_back(path);for (int i = startIndex; i < nums.size(); ++i) {path.push_back(nums[i]);backtracking(nums, i + 1);path.pop_back();}}vector<vector<int>> subsets(vector<int>& nums) {backtracking(nums, 0);return res;}
};