快速排序

问题：找临界点挺难的，是了好几次，终于OK了。

 

代码：

#include <iostream>

using namespace std;

void qSort(int arr[],int left,int right)
{
	int i,j;
	int pos;
	static int count=1;
	if(left>=right)
		return;
	
	i=left;
	j=right;
	int key=arr[i];
	pos=i;
    while(i<j)
	{
		while(i<j&&arr[j]>=key)
		{
			j--;
		}
	    if(i<j&&arr[j]<key)
		{
			arr[pos]=arr[j];
	        arr[j]=key;	
			pos=j;
			j--;
		}
		while(i<=j&&arr[i]<=key)
		{
			i++;
		}
	    if(i<=j&&arr[i]>key)
		{
	       arr[pos]=arr[i];
           arr[i]=key;
		   pos=i;
		   i++;
		}

	}
	cout<<"第"<<count<<"次快速排序-"<<j<<":";
	for(int k=left;k<=right;k++)
		cout<<arr[k]<<"  ";
	cout<<endl;
	count++;
	qSort(arr,left,j);
	qSort(arr,j+1,right);

	
	
}

int main()
{
	int arr[]={8,7,6,5,4,3,2,1};
	cout<<"快速排序前:"<<endl;
	for(int i=0;i<8;i++)
	{
		cout<<arr[i]<<"  ";
	}
	cout<<endl<<endl;
	qSort(arr,0,7);
	cout<<endl;
	cout<<"快速排序后:"<<endl;
	for(int j=0;j<8;j++)
	{
		cout<<arr[j]<<"  ";
	}
	cout<<endl;
	return 0;
}

 运行结果: