快速排序

#include<iostream>  
using namespace std; 
int a[] = {2,3,5,7,9,1,4,6,8,11}; 
int n = 10;  
void swap(int &a,int &b){  
	int tmp = a;  
	a = b;  
	b = tmp;  
}  


int partition(int p,int r){  
	int rnd = rand()%(r-p+1)+p;  
	swap(a[rnd],a[r]);  
	int pvt = r, i = p-1;  
	for(int j = i+1;j<r;j++)  
		if(a[j]<a[pvt])  
			swap(a[j],a[++i]);  
	swap(a[++i],a[pvt]);  
	return i;  
}  


void qsort(int p,int r){  
	if(p<r){  
		int q = partition(p,r);  
		qsort(p,q-1);  
		qsort(q+1,r);  
	}  
}  
int main()
{   
	qsort(0,n-1);  
	for(int i=0;i<n;i++)  
		cout<<a[i]; 
	getchar();
	return 0;  
}