quicksort(快排)

#include<iostream>
#include<stdio.h>
using namespace std;
//显示数组元素
void show(int *a,int n)
{
    for(int i=0;i<n;i++)
    {
	printf("%d",a[i]);
    }
    printf("\n");
}
//快排实现
void sort(int *a,int lowIndex,int hightIndex)
{
    int i = lowIndex;
    int j = hightIndex;
    int key = a[i];
    while(i<j)
    {
	while(i<j && a[j]>=key)
	{
	    j--;
	    //printf("j = %d\n",j);
	}
	if(i<j)
	{
	    a[i++] = a[j];
	}
	while(i<j && a[i]<=key)
	{
	    i++;
	    //printf("i = %d\n",i);
	}
	if(i<j)
	{
	    a[j--]=a[i];
	}
    
    a[i] = key;


    sort(a,lowIndex,i-1);
    sort(a,i+1,hightIndex);
    }

}
//测试
int main()
{
    int a[]={1,4,7,2,5,8,3,6,9};
    int n = sizeof(a)/sizeof(int);
    printf("n = %d\n",n);
    show(a,n);
    sort(a,0,n-1);
    show(a,n);
    return 0;
}