下面C++代码实现输出如下图形，应该在横线处填入的代码是()。

cout << "请输入层数:";
cin >> N;
K = 1;
for (i = 1; i < N + 1; i++){
    for (int _ = 1; _ < ___________; _++)
        cout << " ";
    for (int _ = 1; _ < ________; _++){
        cout << K;
        K += 1;
        if (K == 10) K = 1;
    }
    cout << '\n';
}