Sum of All Subset XOR Totals

class Solution {
public:
    int subsetXORSum(vector<int>& nums) {
        int ans = 0, N = (int)nums.size();
        function<void(int, int)> go = [&](int idx, int x) -> void {
            if(idx == N) {
                ans += x;
                return;
            }
            go(idx + 1, x);
            go(idx + 1, x ^ nums[idx]);
        };
        go(0, 0);
        return ans;
    }
};