//无参有返
public int assd()
{
int sum = 0;
for (int i = 0; i < 7;i++ )
{
if (i == 0)
{
sum = 2;
}
else
{
sum = 2 * (sum + 1);
}

}
return sum;

}
static void Main(string[] args)
{
Program hanshu = new Program();
int s = hanshu.assd();
Console.WriteLine(s);
Console.ReadLine(); 

//有参有返
public int bu(int s)
{ 
int bu = 0;
Random ran = new Random();
for (int i = 0; i < s; i++)
{
int a = ran.Next(1, 7);
bu += a;
if (bu % 10 == 3)
{
bu += 1;
}
else if (bu % 10 == 5)
{
bu -= 1;
}
else if (bu % 10 == 7)
{
bu += 2;
}
else if (bu % 10 == 0)
{
bu -= 4;
}
else
{
continue;
}
}
return bu;
}
static void Main(string[] args)
{
Program hanshu = new Program();
Console.Write("输入您投的次数：");
int x = hanshu.bu(int.Parse(Console.ReadLine()));
Console.WriteLine(x);
Console.ReadLine();

//无参有返
public string d()
{
Random ran = new Random();
int fen = 0;
int i = 1;
int c = 0;
for (; ; )
{
int s = ran.Next(1, 21);
if (s < 17)
{
c++;
if (c == 5)
{
fen -= 2;
c = 0;
}
}
else if (s < 20)
{
fen += 4;
}
else
{
fen += 7;
}
i++;
if (fen >= 100)
{
break;
}
}
return "需要" + i + "次，才能达到100分";
}
static void Main(string[] args)
{
Program hanshu = new Program();
string s = hanshu.d();
Console.WriteLine(s);
Console.ReadLine();