subsets.cpp

class Solution {
    void subsets_rec(vector<int>& nums, int idx, vector<vector<int>>& result ){
        if(idx == nums.size()-1){
            result.push_back({});
            result.push_back({nums[idx]});
            
        }
        else{
            subsets_rec(nums, idx+1,result);
            int n = result.size();
            for (int i =0;i<n;++i){
                vector<int> r = result[i];
                r.push_back(nums[idx]);
                result.push_back(r);
            }
        }
    }
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        if(nums.empty() ) return {{}};
        vector<vector<int>> result;
        
        subsets_rec(nums, 0, result);
        return result;
        
    }
};