C#七大经典排序算法系列（下）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InsertSort
{
 public class Program
 {
  static void Main(string[] args)
  {
   List<int> list = new List<int>() { 3, 1, 2, 9, 7, 8, 6 };

   Console.WriteLine("排序前：" + string.Join(",", list));

   InsertSort(list);

   Console.WriteLine("排序后：" + string.Join(",", list));
  }

  static void InsertSort(List<int> list)
  {
   //无须序列
   for (int i = 1; i < list.Count; i++)
   {
    var temp = list[i];

    int j;

    //有序序列
    for (j = i - 1; j >= 0 && temp < list[j]; j--)
    {
     list[j + 1] = list[j];
    }
    list[j + 1] = temp;
   }
  }
 }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Diagnostics;

namespace ShellSort
{
 public class Program
 {
  static void Main(string[] args)
  {
   //5次比较
   for (int i = 1; i <= 5; i++)
   {
    List<int> list = new List<int>();

    //插入1w个随机数到数组中
    for (int j = 0; j < 10000; j++)
    {
     Thread.Sleep(1);
     list.Add(new Random((int)DateTime.Now.Ticks).Next(10000, 1000000));
    }

    List<int> list2 = new List<int>();
    list2.AddRange(list);

    Console.WriteLine("\n第" + i + "次比较：");

    Stopwatch watch = new Stopwatch();

    watch.Start();
    InsertSort(list);
    watch.Stop();

    Console.WriteLine("\n插入排序耗费的时间：" + watch.ElapsedMilliseconds);
    Console.WriteLine("输出前十个数:" + string.Join(",", list.Take(10).ToList()));

    watch.Restart();
    ShellSort(list2);
    watch.Stop();

    Console.WriteLine("\n希尔排序耗费的时间：" + watch.ElapsedMilliseconds);
    Console.WriteLine("输出前十个数:" + string.Join(",", list2.Take(10).ToList()));

   }
  }

  ///<summary>
/// 希尔排序
///</summary>
///<param name="list"></param>
  static void ShellSort(List<int> list)
  {
   //取增量
   int step = list.Count / 2;

   while (step >= 1)
   {
    //无须序列
    for (int i = step; i < list.Count; i++)
    {
     var temp = list[i];

     int j;

     //有序序列
     for (j = i - step; j >= 0 && temp < list[j]; j = j - step)
     {
      list[j + step] = list[j];
     }
     list[j + step] = temp;
    }
    step = step / 2;
   }
  }

  ///<summary>
/// 插入排序
///</summary>
///<param name="list"></param>
  static void InsertSort(List<int> list)
  {
   //无须序列
   for (int i = 1; i < list.Count; i++)
   {
    var temp = list[i];

    int j;

    //有序序列
    for (j = i - 1; j >= 0 && temp < list[j]; j--)
    {
     list[j + 1] = list[j];
    }
    list[j + 1] = temp;
   }
  }
 }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MergeSort
{
 class Program
 {
  static void Main(string[] args)
  {
   int[] array = { 3, 2, 1, 8, 9, 0 };

   MergeSort(array, new int[array.Length], 0, array.Length - 1);

   Console.WriteLine(string.Join(",", array));
  }

  ///<summary>
/// 数组的划分
///</summary>
///<param name="array">待排序数组</param>
///<param name="temparray">临时存放数组</param>
///<param name="left">序列段的开始位置，</param>
///<param name="right">序列段的结束位置</param>
  static void MergeSort(int[] array, int[] temparray, int left, int right)
  {
   if (left < right)
   {
    //取分割位置
    int middle = (left + right) / 2;

    //递归划分数组左序列
    MergeSort(array, temparray, left, middle);

    //递归划分数组右序列
    MergeSort(array, temparray, middle + 1, right);

    //数组合并操作
    Merge(array, temparray, left, middle + 1, right);
   }
  }

  ///<summary>
/// 数组的两两合并操作
///</summary>
///<param name="array">待排序数组</param>
///<param name="temparray">临时数组</param>
///<param name="left">第一个区间段开始位置</param>
///<param name="middle">第二个区间的开始位置</param>
///<param name="right">第二个区间段结束位置</param>
  static void Merge(int[] array, int[] temparray, int left, int middle, int right)
  {
   //左指针尾
   int leftEnd = middle - 1;

   //右指针头
   int rightStart = middle;

   //临时数组的下标
   int tempIndex = left;

   //数组合并后的length长度
   int tempLength = right - left + 1;

   //先循环两个区间段都没有结束的情况
   while ((left <= leftEnd) && (rightStart <= right))
   {
    //如果发现有序列大，则将此数放入临时数组
    if (array[left] < array[rightStart])
     temparray[tempIndex++] = array[left++];
    else
     temparray[tempIndex++] = array[rightStart++];
   }

   //判断左序列是否结束
   while (left <= leftEnd)
    temparray[tempIndex++] = array[left++];

   //判断右序列是否结束
   while (rightStart <= right)
    temparray[tempIndex++] = array[rightStart++];

   //交换数据
   for (int i = 0; i < tempLength; i++)
   {
    array[right] = temparray[right];
    right--;
   }
  }
 }
}