牛牛算法整理

      List listpk = new List { 2, 1, 3, 5, 10 };
            int count = listpk.Count;
            int sum = 0;
            int lave = 0;
            for (int i = 0; i < count; i++)
            {
                if (listpk[i] > 10)
                    listpk[i] = 10;//方便将J Q K转换成十，如果存储了逻辑值可以忽略这一步
                sum += listpk[i];
            }
            lave = sum % 10;
            for (int i = 0; i < count - 1; i++)
            {
                for (int j = i + 1; j < count; j++)
                {
                    if ((listpk[i] + listpk[j]) % 10 == lave)
                    {
                        if (lave == 0)
                        {
                            Console.WriteLine("牛" + 10);
                        }
                        else
                        {
                            Console.WriteLine("牛" + lave);
                        }
                    }
                }
            }

第二种方法；

bool flag = false;

   for(int i = 0;i < count - 2;i++)
    {
                for(int j = i + 2;j < count;j++)
                {
                    sum = arr[i] + arr[i+1] + arr[j];
                    if(sum%10 == 0)
                    {
                        Console.WriteLine("等待五秒");
                        Console.WriteLine("存在10");
                        flag = true;
                    }  
                }
                if(flag)
                    break;
            }