powerSet.cpp

#include <iostream>
#include <vector>
using namespace std;

class Solution {
   private:
    void solve(vector<int> nums, vector<int> output, int index, vector<vector<int>>& ans) {
        // base case
        if (index >= nums.size()) {
            ans.push_back(output);
            return;
        }

        // exclude
        solve(nums, output, index + 1, ans);

        // include
        int element = nums[index];
        output.push_back(element);
        solve(nums, output, index + 1, ans);
    }

   public:
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> ans;
        vector<int> output;
        int index = 0;
        solve(nums, output, index, ans);
        return ans;
    }
};

int main() {
    Solution s;
    s.subsets();
    return 0;
}