int i,j;
int last, N;

cout << "请输入层数N：";
cin >> N;

last = 1;
for (i = 1; i < N; i++){
    for (j = 1; j < i + 1; j++){ // L1
        if (last > 9)
            last = 1;

        cout << last << " ";
        last += 1;
    }
    printf("\n");
}
请输入层数N：10
1
2 3
4 5 6
7 8 9 1
2 3 4 5 6
7 8 9 1 2 3
4 5 6 7 8 9 1
2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9