C++用循环语句输出“*”

求解如何输出下面这段符号啊，思路是什么，快来帮我解答一下😭
*
***

---

---

---

  ***
     *

C++:

#include <iostream>
using namespace std;
 
int main ()
{
   // for 循环执行
   for( int a = 1; a < 10; a += 2 )
   {
       for (int i=1;i<=a;i++)
       cout<< "*";
       cout<<endl;
   }
   return 0;
}