做练习

输入人数，输入每个人的成绩
需要最高分、最低分，
去掉两个最高分，去掉两个最低分，求平均分。

 Console.Write("请输入班级人数：");
            int shu = int.Parse(Console.ReadLine());
            int[] fen = new int[shu];
            if (shu >= 5)
            {
                for (int i = 0; i < shu; i++)
                {
                    Console.Write("请输入第" + (i + 1) + "个人的成绩:");
                    fen[i] = int.Parse(Console.ReadLine());
                }
                for (int i = 0; i < shu; i++)
                {
                    for (int j = i; j < shu - 1; j++)
                    {
                        if (fen[i] < fen[j + 1])
                        {
                            int zhong;
                            zhong = fen[i];
                            fen[i] = fen[i + 1];
                            fen[i + 1] = zhong;
                        }
                    }
                }
                double sum = 0;
                Console.WriteLine("最高分为：" + fen[0] + "最低分为:" + (fen[fen.Length - 1]));
                for (int i = 2; i <= (fen[fen.Length - 3]); i++)
                {
                    sum = fen[i];
                }
                Console.WriteLine("平均分为：" + (sum / (shu - 4)));
            }
            else
            {
                Console.WriteLine("您输入的人数要大于等于5！");
            }
            Console.ReadLine();

例：

抽奖活动：
输入n个手机号码，滚动号码，5秒钟后停止
输出中奖人号码

Console.Write("请输入手机号码个数：");
            int a = int.Parse(Console.ReadLine());
            string[] shuzu = new string[a];
            for (int i = 0; i < a; i++)
            {
                Console.Write("请输入第" + (i + 1) + "个手机号码：");
                shuzu[i] = Console.ReadLine();
            }
            Console.WriteLine("所有号码输入完毕，请按回车键开始滚动号码！");
            Console.ReadLine();
            Random ran = new Random();
            int r = 0;
            for (; ; )
            {
                int aa = ran.Next(a);
                Console.Clear();
                Console.WriteLine(shuzu[aa]);
                System.Threading.Thread.Sleep(100);

                if (r == 49)
                {
                    //作弊代码
                    //Console.Clear();
                    //Console.WriteLine("110");
                    break;
                }
                r++;
            }
            Console.ReadLine();