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],
[]
]
分析： 用位操作非常简单，对于n个数来说共有2^n个组合，每一个组合中n个数的每一个 在或者不在 两种情况
class Solution {
public:
vector<vector<int>> subsets(vector<int>& nums) {
int n=nums.size();
int total = pow(,n);
vector<vector<int>> res(total);
for(int i=; i<n; i++){
for(int j=; j<total; j++){
if(j>>i & )
res[j].push_back(nums[i]);
}
}
return res;
}
};