78 Subsets

Given a set of distinct integers, nums, return all possible subsets.
Note: The solution set must not contain duplicate subsets.
For example, If nums = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Solution:

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