My code is as below, I am curious about how to improve the performance since the ranking is only 6.27%?

```
class Solution {
public:
vector<vector<int>> subsets(vector<int>& nums) {
int n = nums.size();
vector<vector<int>>result;
long long range = 1 << n;
for (long long i = 0; i < range; i++)
{
result.push_back(vector<int>());
long long t = i, s=0;
while (t)
{
if (1 & t)result[result.size() - 1].push_back(nums[s]);
s++;
t >>= 1;
}
}
return result;
}
};
```