快速排序——算法系列

快速排序：

思想：主要是利用了分而治之的思想，将一个大的排序问题简化成一个一个小的问题。

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<int> list = new List<int>();//插入2k个随机数到数组中for (int j = 0; j < 2000; j++){Thread.Sleep(1);list.Add(new Random((int)DateTime.Now.Ticks).Next(0, 100000));}Console.WriteLine("\n第" + i + "次比较：");Stopwatch watch = new Stopwatch();watch.Start();var result = list.OrderBy(single => single).ToList();//这里这个single=>single不懂
                watch.Stop();Console.WriteLine("\n系统的快速排序耗费时间：" + watch.ElapsedMilliseconds);Console.WriteLine("输出前是十个数："+string.Join(",",result.Take(10).ToList()));
                watch.Start();new QuickSortClass().QuickSort(list, 0, list.Count - 1);watch.Stop();Console.WriteLine("\n自己的快速排序耗费时间：" + watch.ElapsedMilliseconds);Console.WriteLine("输出前是十个数：" + string.Join(",", result.Take(10).ToList()));//这里也不是很懂
                }Console.ReadLine();}//快速排序算法
    }public class QuickSortClass{private int Division(List<int> list, int left, int right){int baseNum = list[left];while (left < right){while (left < right && baseNum <= list[right])right--;list[left] = list[right];while (left < right && baseNum >= list[left])left++;list[right] = list[left];}list[left] = baseNum;return left;}public void QuickSort(List<int> list, int left, int right){if (left < right){int i = Division(list, left, right);QuickSort(list, left, i - 1);QuickSort(list, i + 1, right);}}}
}