1.1

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace Test1_1

{

    class Program

    {

        static void Main(string[] args)

        {

            int n = int.Parse(Console.ReadLine());

            int oddn=0;

            int evenn=0;

            if (n % 2 != 0)

            {

                for (int i = 1; i <= n; i++)

                {

                    if (i % 2 != 0)

                    {

                        oddn = oddn + i;

                    }

                }

                Console.WriteLine("奇数和为:{0}", oddn);

            }

            else

            {

                for (int j = 1; j <= n; j++)

                {

                    if (j % 2 == 0)

                    {

                        evenn = evenn + j;

                    }

                }

                Console.WriteLine("偶数和为:{0}", evenn);

            }

            Console.Read();

        }

    }

}

1.11

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Security.Cryptography;

using System.Text;

using System.Threading.Tasks;

namespace Test1_11

{

    class Program

    {

        static void Main(string[] args)

        {

            //string s_text, s_key, s_result = null;

            //char ch;

            //Console.WriteLine("请输入原字符串：");

            //s_text = Console.ReadLine();

            //int m = s_text.Length;  //原文字符串长度

            //Console.WriteLine(s_text);

            //Console.WriteLine("请输入密钥字符串：");

            //s_key = Console.ReadLine();

            //int n = s_key.Length;  //密钥字符串长度

            //if(m!=n)

            //{

            //    Console.WriteLine("密钥字符串与原文字符串长度必须相等");

            //}

            //else

            //{

            //    for(int i=0;i<m;i++)

            //    {

            //    }       这种加密方式不会

            TripleDESCryptoServiceProvider tDCtSP = new TripleDESCryptoServiceProvider();

            MemoryStream ms = new MemoryStream();

            ICryptoTransform crypt = tDCtSP.CreateEncryptor();

            Console.WriteLine("请输入原字符串：");

            string data = Console.ReadLine();

            UTF8Encoding utf = new UTF8Encoding();

            byte[] databyte = utf.GetBytes(data); 

            CryptoStream cts = new CryptoStream(ms, crypt, CryptoStreamMode.Write);

            cts.Write(databyte, 0, databyte.Length);

            cts.Close();

            byte[] msdata = ms.ToArray();

            Console.WriteLine(utf.GetString(msdata));

            Console.Read();

        }

    }

}