排序----快速排序

/****
****采用三数中值法选区枢纽元
****在数据小于一定值时采用插入排序可以实现更高效率的排序
****
****
****
****
****/
#include <iostream>
#define cutoff 3
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
template <class Type>
void swap(Type &a, Type &b)
{
	Type temp;
	temp = a;
	a = b;
	b = temp;
}
template<class Type>
void InsertSort(Type A[], int N)
{
	int i, j;
	Type temp;
	for (i = 1; i<N; i++)
	{
		temp = A[i];
		for (j = i; j >= 0 && A[j - 1]>temp; j--)
			A[j] = A[j - 1];
		A[j] = temp;
	}
}

//以三数中值作为基准值 
template <class Type>
Type Median3(Type A[], int left, int right)
{
	int center = (left + right) / 2;
	if (A[left]>A[center])
		swap(A[left], A[center]);
	if (A[left]>A[right])
		swap(A[left], A[right]);
	if (A[center]>A[right])
		swap(A[center], A[right]);
	//以上得到A[left]<=A[center]<=A[right]
	swap(A[center], A[right - 1]);//隐藏枢纽元
	return A[right - 1];	       //返回枢纽元 
}
template <class Type>
void QSort(Type A[], int left, int right)
{
	int i, j;
	Type Pivot;
	Pivot = Median3(A, left, right);
	i = left; j = right - 1;
	if (left + cutoff <= right)
	{
		for (;;)
		{
			while (A[++i]<Pivot){}
			while (A[--j]>Pivot){}
			if (i<j)
				swap(A[i], A[j]);
			else
				break;

		}

		swap(A[i], A[right - 1]);//将枢纽元换回
		QSort(A, left, i - 1);
		QSort(A, i + 1, right);
	}
	
	
	else
	InsertSort(A+left,right-left+1);
}
int main(int argc, char *argv[]) {
	int A[10] = { 2, 5, 1, 3, 43, 6,21,32,78,76 };
	QSort(A, 0, 9);
	//QSort();
	//swap(A[0],A[1]); 
	for (int i = 0; i<10; i++)
		std::cout << A[i] << std::endl;
	return 0;
}