Musical Scales Solution:

import java.util.*;
//https://open.kattis.com/problems/musicalscales
public class Kattis {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int numNotes = Integer.parseInt(sc.nextLine());
    String[] input = sc.nextLine().split(" ");
    String[] notes = {"A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#"};
    int[] major = {2, 2, 1, 2, 2, 2, 1};
    int curr = 0;
    boolean exists = false;
    //each major
    major:
    for (int i = 0; i < notes.length; i++) {
      curr = i;
      HashSet<String> hs = new HashSet<>(Arrays.asList(input));
      //System.out.print(notes[i] + " ");
      //stepping in major
      for (int j = 0; j < major.length; j++) {
        curr += major[j];
        hs.remove(notes[curr % notes.length]);
        if (hs.isEmpty()) {
          System.out.print(notes[i] + " ");
          exists = true;
          continue major;
        }
      }
      //System.out.print(notes[curr%notes.length] + " ");
    }
    if (!exists) {
      System.out.println("none");
    }
  }
}