Coloring cube

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    int n;
    cin >> n;
    int prevFaceLetter;
    int prevLineLetter;
    int currentLetter = 0;
    char letters[] = {'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(j == 0 && k == 0){
                    prevFaceLetter = currentLetter;
                }
                if (k == 0)
                {
                    prevLineLetter = currentLetter;
                }
                cout << letters[currentLetter];
                if (k < n - 1)
                {
                    cout << " ";
                }
                currentLetter = (currentLetter + 1) % 3;
            }
            currentLetter = (prevLineLetter + 1) % 3;
            cout << endl;
        }
        currentLetter = (prevFaceLetter + 1) % 3;
        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