Coloring cube

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

#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)

typedef long long ll;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  const size_t SIZE = 3;
  char color[SIZE] = {'R', 'G', 'B'};

  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      for (int k = 0; k < n; k++) {
        if (k != 0)
          cout << " ";
        cout << color[(k+i+j) % SIZE];
      }
      cout << endl;
    }
    cout << 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