代码随想录：子集

就是组合

class Solution {
public:
    vector<int> path;
    vector<vector<int>> res; 

    vector<vector<int>> subsets(vector<int>& nums) {
        res.push_back(path);
        rb(nums,0);
        return res;
    }

    void rb(vector<int>& nums,int start){
        for(int i=start;i<nums.size();i++){
            path.push_back(nums[i]);
            res.push_back(path);
            rb(nums,i+1);
            path.pop_back();
        }
    }
};