leetcode

0078.cpp (363B)

 class Solution {
   public:
     vector<vector<int>> subsets(vector<int> &nums) {
         vector<vector<int>> res;
 
         res.push_back({});
         for (int num : nums) {
             for (int i = res.size() - 1; i >= 0; i--) {
                 res.push_back(res[i]);
                 res.back().push_back(num);
             }
         }
         return res;
     }
 };