现有1~100 共一百个自然数,已随机放入一个有98个元素的数组a[98].要求写出一个尽量简单的方案找出没有被放入数组的那2个数,并在屏幕上打印这2个数

  void test7()
         {
             try
             {
                 int[] a = new int[];
                 int[] num = new int[];
                 int[] num1 = new int[];
                 int countnum = ;
                 int counta = ;
                 int i;
                 for (i = ; i < num.Length; i++)
                 {
                     num[i] = i + ;
                     num1[i] = i + ;//方法1用到
                     countnum = num[i] + countnum;
                 }
                 //随机放入
                 Random rand = new Random();
                 int temp;
                 for (i = ; i < a.Length; i++)
                 {
                     while (true)
                     {
                         temp = rand.Next();
                         if (num[temp] != )
                         {
                             num[temp] = ;
                             a[i] = temp + ;
                             break;
                         }
                     }
                 }
                 foreach (int aa in a)
                 {
                     counta = counta + aa;

                     Console.WriteLine(aa+";");
                 }

                 #region 方法1 推荐，这才是插入完，再查找
                 int diff = countnum - counta;
                 List<int> list = num.Where(n => num.Contains(diff - n)).ToList<int>();//验证,num中只剩两个没变0的
                 List<int> list1 = num1.Where(n => num1.Contains(diff - n) && !a.Contains(n)).ToList<int>();//查找，针对的是没有处理过得原数组
                 Console.WriteLine("list.count:"+list.Count);
                 Console.WriteLine("list1.count:" + list1.Count);
                 foreach (int nn in list)
                 {
                     //if (!a.Contains(nn))
                     //{
                     Console.WriteLine("没有被放入数组的数(list)：");
                         Console.WriteLine(nn);
                         //Console.WriteLine("bingo");
                     //}
                 }
                 foreach (int nn in list1)
                 {
                     //if (!a.Contains(nn))
                     //{
                     Console.WriteLine("没有被放入数组的数(list1)：");
                         Console.WriteLine(nn);
                         //Console.WriteLine("bingo1");
                     //}
                 }
                 #endregion

                 #region 方法2 太投机取巧了，其实是在随机插入的过程中把插入的全置为0，剩下的就是没插入的
                 for (i = ; i < a.Length; i++)
                     if (num[a[i] - ] != )
                         num[a[i] - ] = ;
                 //输出
                 for (i = ; i < a.Length; i++)
                 {
                     if (i %  ==  && i > )
                         System.Console.WriteLine();
                     System.Console.Write("{0,4}", a[i]);
                 }
                 System.Console.WriteLine();
                 System.Console.Write("没有被放入数组的2个数：");
                 for (i = ; i < num.Length; i++)
                     if (num[i] != )
                         System.Console.Write("{0,4}", num[i]);
                 System.Console.WriteLine();
                 #endregion
             }
             catch (Exception)
             {

                 throw;
             }
         }