//直接輸出n即可

void tower(int n, char a, char b, char c)
{
    if (n == 1)
    {
        printf("Move ring %d from %c to %c\n",n,a,c);
    }
    else {
        tower(n - 1, a,c,b);
        printf("Move ring %d from %c to %c\n", n, a, c);
        tower(n-1, b, a, c);
    }
}