Coloring cube

#include <iostream>
#include <vector>
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

char ll_to_color(ll a) {
    if(a == 0) return 'R';
    else if(a == 1) return 'B';
    else return 'G';
}

int main() {
    ll n;
    cin >> n;

    ll a[n];

    ll color_id = 0;
    for (ll i = 0; i < n; i++) {
        if(i>n && a[i-n] == color_id) {
            color_id = (color_id + 1)%3;
        } 
        a[i] = color_id%3;
        color_id = (color_id + 1)%3;
    }

    for(ll k = 0; k < n; k++) {
        for (ll i = 0; i < n; i++) {
            for(ll j = 0; j<n; j++) {
                cout << ll_to_color((a[j]+i+k)%3) << " ";
            }
            cout << endl;
        }
        cout << endl;
    }
    


}

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