public static void doAssignment(int num)
{
    int rowNum = 0;
    for (int i = 0; i < num; i++)
    {
        for (int j = 1; j <= i; j++)
        {
            Console.Write("* ");
        }
        for (int j= 0; j < num - rowNum; j++)
        {
            Console.WriteLine();
        }
        for (int j=0; j <= i; j++)
        {
            Console.Write("* ");
        }
        rowNum++;
    }
}