/*
 * @lc app=leetcode.cn id=78 lang=cpp
 *
 * [78] 子集
 */

// @lc code=start
class Solution {
    vector<int> track;
    vector<vector<int>> res;

    void backtrack(vector<int>& nums, int start) {
        res.emplace_back(track);

        for (int i = start; i < nums.size(); ++i) {
            track.emplace_back(nums[i]);
            backtrack(nums, i + 1);
            track.pop_back();
        }
    }
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        backtrack(nums, 0);
        return res;
    }
};
// @lc code=end