快速排序

属于冒泡排序的升级， 都属于交换排序类。即它也是通过不断比较和移动来实现排序的，只不过它的实现，增大了记录的比较和移动的距离，将关键字较大的记录从前面直接移动到后面，关键字较小的记录从后面直接移动到前面，从而减少了比较次数和移动交换次数。

using System;
using System.Linq;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] sqList = new int[] { 97, 0, 5, 4, 3, 1, 5, 9, 11, 13 };
            QuickSort(sqList);
            sqList.ToList().ForEach(s => Console.Write(s + " "));
            Console.ReadLine();
        }

        static void QuickSort(int[] sqList)
        {
            QSort(sqList, 0, sqList.Length-1);
        }

        static void QSort(int[] sqList, int low, int high)
        {
            int pivot;
            if (low < high)
            {
                pivot = Partition(sqList, low, high);

                QSort(sqList, low, pivot - 1);
                QSort(sqList, pivot + 1, high);
            }
        }

        static int Partition(int[] sqList, int low, int high)
        {
            int pivotkey = sqList[low];
            while (low < high)
            {
                while (low < high && sqList[high] >= pivotkey) 
                {
                    high--;
                }

                Swap(sqList, low, high); //将比枢轴值小的记录交换到低端

                while (low < high && sqList[low] <= pivotkey)
                {
                    low++;
                }

                Swap(sqList, low, high); //将比枢轴值大的记录交换到高端
            }

            return low; //返回枢轴所在位置
        }

        static void Swap(int[] sqList, int index1, int index2)
        {
            int value1 = sqList[index1];
            sqList[index1] = sqList[index2];
            sqList[index2] = value1;
        } 
    }
}