Counting ones

#include <bits/stdc++.h>
using namespace std;

#define I_2D(row, col, width) ((row) * (width) + (col))
#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)
#define PRINT_VEC_ARR(v, n)                                                    \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << i << ": ";                                                       \
      for (auto item : v[i]) {                                                 \
        cout << item << " ";                                                   \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  } while (0)

typedef unsigned long ll;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  ll arr[n];

  int fi = 0, si = 0;
  ll max_ones = 0;

  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }

  ll ones;
  for (int i = 0; i < n; i++) {
    for (int j = i+1; j < n; j++) {
      ones = __builtin_popcountll(arr[i]*arr[j]);
      if (ones > max_ones) {
        fi = i;
        si = j;
        max_ones = ones;
      }
    }
  }
  cout << max_ones << endl;
  cout << arr[fi] << " " << arr[si] << endl;
  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED