Subsets Leetcode C++ solution

subsets.cpp

ITERATIVE SOLUTION 

``` 
class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        vector< vector <int> > res(1,vector<int>());
        sort(nums.begin(),nums.end());
        for (int i=0;i<int(nums.size());i++){
            int n=res.size();
            for (int j=0;j<n;j++){
                res.push_back(res[j]);
                res.back().push_back(nums[i]);
            }
        }
        return res;
    }
};
```



Bit-manipulation 
```
class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        int n=nums.size();
        int p=1<<n;
        vector <vector <int>> res(p);
        for (int i=0;i<p;i++){
            for (int j=0;j<n;j++){
                if ((i>>j)& 1){
                    res[i].push_back(nums[j]);
                }
            }
        }
       return res; 
    }
};
```