Subsets (C++)

subsets.cc

class Solution {
public:
    /**
     * @param nums: A set of numbers
     * @return: A list of lists
     */
    vector<vector<int>> subsets(vector<int> &nums) {
        if (nums.size() == 0) {
            vector<vector<int>> res;
            vector<int> empty;
            res.push_back(empty);
            return res;
            //return {{}}; // empty vector
        }
        // sort 
        std::sort(nums.begin(), nums.end());
        // problem: n-1
        vector<int> sub = nums;
        sub.erase(sub.end() - 1);
        vector<vector<int>> subs = subsets(sub);
        // problem: n
        vector<vector<int>> res = subs;
        for (auto& s: subs) {
            s.push_back(nums[nums.size() - 1]);
            res.push_back(s);
        }
        return res;
    }
};