//优化后的快速排序代码：1、优化基准点的选取 2、优化不必要的交换
#include<iostream>
#include"stdio.h"
using namespace std;
void swap(int k[], int low, int high)
{
int temp;
temp = k[low];
k[low] = k[high];
k[high] = temp;
}
int Partition(int k[],int low,int high)//计算基准点函数，把小于基准点的数移到左边，把大于基准点的数移到右边
{
int point;
//优化1（以下）
int m = low + (high - low) / 2;//如果数组为{7,6,5,4,3,2,1}，直接选择基准点k[low]=7需要交换的次数太多了，所以需要重新处理一下
if (k[low]>k[high])
{
swap(k,low,high);
}
if (k[m] >k[high])
{
swap(k, m, high);
}
if (k[m]>k[low])
{
swap(k, m, low);
}
//优化1（以上）
point = k[low];
while (low<high)
{
while (low < high&&k[high] >= point)
{
high--;//从右边半数组中过滤掉比point大的元素，不需要交换
}
k[low] = k[high];//如果比point小，则需要交换，//2、优化不必要的交换 把swap(k,low,high)改为： k[low] = k[high]
while (low < high&&k[low] <= point)
{
low++;
}
k[high] = k[low];//2、优化不必要的交换 把swap(k,low,high)改为：k[high] = k[low]
}
k[low] = point;
return low;
}
void Qsort(int k[],int low,int high)//快速排序
{
int point;//存放基准点的值
if (low < high)
{
point = Partition(k,low,high);
Qsort(k,low,point-1);
Qsort(k, point+1, high);
}
}
void QuickSort(int k[], int n)
{
Qsort(k, 0, n - 1);
}
int main()
{
int a[10] = { 5, 2, 6, 0, 3, 9, 1, 7, 4, 8 };
int i;
QuickSort(a, 10);
printf("排序后的结果是：");
for (i = 0; i < 10; i++)
{
printf("%d", a[i]);
}
printf("\n");
return 0;
}Result of the program: 0123456789