leetcode

0 class Solution {

1 public:

2 vector<int> sortByBits(vector<int> &arr) const {

3 sort(begin(arr), end(arr), [](int a, int b) {

4 const int x = __builtin_popcount(a);

5 const int y = __builtin_popcount(b);

6 return x != y ? x < y : a < b;

7 });

8 return arr;

9 }

10 };