希尔排序：

插入排序的升级版，主要采用了分组的策略，采用逐渐减小步长来控制分组的大小，各组内采用插入排序，当步长减小为1的时候，大部分数据都已经有序，所以较插入排序优化了许多。

代码：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Diagnostics;using System.Net;using System.Threading;namespace ConsoleApplication1{    class Program    {        static void Main(string[] args)        {            for (int i = 1; i <= 5; i++)            {                List
     
       list = new List
      
       ();                //插入2k个随机数到数组中                for (int j = 0; j < 20000; j++)                {                    Thread.Sleep(1);                    list.Add(new Random((int)DateTime.Now.Ticks).Next(10000, 1000000));                }                Console.WriteLine("\n第" + i + "次比较：");                Stopwatch watch = new Stopwatch();                watch.Start();                var result = ShellSort(list);//这里这个single=>single不懂                watch.Stop();                Console.WriteLine("\n希尔排序耗费时间：" + watch.ElapsedMilliseconds);                Console.WriteLine("输出前是十个数："+string.Join(",",result.Take(10).ToList()));                watch.Start();                result = InsertSort(list);                watch.Stop();                Console.WriteLine("\n插入排序耗费时间：" + watch.ElapsedMilliseconds);                Console.WriteLine("输出前是十个数：" + string.Join(",", result.Take(10).ToList()));                            }                        Console.ReadLine();        }        static List
       
         ShellSort(List
        
          list)        {            int step = list.Count / 2;            while (step >= 1)            {                for (int i = step; i < list.Count; i++)                {                    int temp = list[i];                    int j;                    for (j = i - step; j >= 0 && temp < list[j]; j = j - step)                    {                        list[j + step] = list[j];                    }                    list[j + step] = temp;                }                step = step / 2;            }            return list;        }        //插入排序算法        static List
         
           InsertSort(List
          
            list) { for (int i = 1; i < list.Count; i++) { int temp = list[i]; int j; for (j = i - 1; j >= 0 && temp < list[j]; j--) { list[j + 1] = list[j]; } list[j + 1] = temp; } return list; } }}
          
         
        
       
      
     

不过这里有个问题，我的希尔排序并不比插入排序快多少，不知道问题出在哪里。。。。。待解决