一些基本笔试

  #region 递归
        private static int sum(int num)
        {
            if (num == 0)
            {
                return 1;
            }
            else {
                return num+sum(num - 1);
            }
        }
        #endregion

  #region 冒泡排序
        private static void Maopao()
        {
            int[] array =new int[] { 20,5,4,5,8 };
            int temp;
            for (int i = 0; i <array.Length-1; i++)
            {
                for (int j = i+1; j < array.Length; j++)
                {
                    if (array[j]<array[i])
                    {
                        temp = array[j];
                        array[j] = array[i];
                        array[i] = temp;
                    }
                }

            }
            for (int i = 0; i < array.Length; i++)
            {
                Console.WriteLine(array[i]);
            }
           
            Console.ReadKey();
        }
        #endregion

 #region 去除重复
        private static void Dis()
        {
            int [] array ={10,20,10,3,2,2,5};
            List<int> list = new List<int>();

            for (int i = 0; i < array.Length-1; i++)
            {
                Console.WriteLine("list.IndexOf(array[i]):{0}", list.IndexOf(array[i]));
                if (list.IndexOf(array[i])==-1)
                {
                    list.Add(array[i]);
                }
               
            }
            String[] s = { "a", "b", "b", "c" };
            String[] q = s.Distinct().ToArray();
            for (int i = 0; i < q.Length-1; i++)
            {
                 Console.WriteLine("q:{0}", q[i]);
            }

            foreach (var item in list)
            {
                Console.WriteLine("list:{0}", item);
            }

            List<int> list1 = new List<int>();
            list1.Add(10);
            list1.Add(11);
            list1.Add(12);
            list1.Add(10);
            var disList = list1.Distinct();
            foreach (var item in disList)
            {
                Console.WriteLine("list1:{0}", item);
            }

            Console.ReadKey();
        }
        #endregion

  #region 字符串反转
        private static void Fanzhuan()
        {
            string str = "我是好人";
           // List<string> list = new List<string>();
            for (int i = str.Length-1; i >=0; i--)
            {
                Console.WriteLine(str.Substring(i,1));
            }
            Console.ReadKey();
        }
        #endregion