判断是否为数独数组

实现代码：

  public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[] freq = new int[10]; // 1~9
        
        for (int i = 0; i < n; i++) {
            int x = scanner.nextInt();
            freq[x]++;
        }
        
        int q = n / 9;
        int r = n % 9;
        
        int countPlusOne = 0;
        boolean possible = true;
        for (int i = 1; i <= 9; i++) {
            if (freq[i] != q && freq[i] != q + 1) {
                possible = false;
                break;
            }
            if (freq[i] == q + 1) {
                countPlusOne++;
            }
        }
        
        if (countPlusOne != r) {
            possible = false;
        }
        
        System.out.println(possible ? "YES" : "NO");
    }