快排：// 修改自《C programing language》

 

#include
    
     #include
     
      #include
      
       void qsort(int v[], int left, int right){	int i,last;	if(left >= right)		return;	std::swap(v[left],v[(left+right)/2]);	last = left;	for(i = left+1; i <= right; ++i)	{		if(v[i] < v[left])			std::swap(v[i],v[++last]);	}	std::swap(v[left],v[last]);	qsort(v,left,last-1);	qsort(v,last+1,right);}int main(){	int a[]={5,3,1,6,8,9,4};	qsort(a,0,7-1);	std::copy(a,a+7,std::ostream_iterator
       
        (std::cout," "));		return 0;}