class Solution {
public:
int res = 0;
int subsetXORSum(vector<int>& nums) {
int n = nums.size();
int res = 0;
for(int i = 0;i < 1 << n;++i){
int s = 0;
for(int j = 0;j < n;++j){
if(i >> j & 1){
s ^= nums[j];
}
}
res += s;
}
return res;
}
};