78. Subsets

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