477. Total Hamming Distance

class Solution {
public:
    int totalHammingDistance(vector<int>& nums) {
        int res = 0;
        for (int i = 0; i < 32; i++) {
            int ones = 0;
            for (int n : nums) {
                if (n & (1 << i)) {
                    ones++;
                }
            }
            res += ones * (nums.size()-ones);
        }
        return res;
    }
};