快速排序递归算法

#include<iostream>
using namespace std;

void Swap(int* x, int *y)
{
int tmp = *x;
*x = *y;
*y = tmp;
}

int Median(int* 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]);
Swap(&a[center], &a[right - 1]);
return a[right-1];
}

int Partition(int *a, int length, int left, int right)
{
if (a == NULL || length < 0 || left<0 || right>length)
throw new exception("Invaild data");
int pivot=Median(a, left, right);
int l = left;
int r = right - 1;
while (l < r)
{
while (a[++l] < pivot);
while (a[--r] > pivot);
if (l < r)
Swap(&a[l], &a[r]);
else
break;
}
Swap(&a[l], &a[right - 1]);
return l;
}

void QuickSort(int *a, int length, int left,int right)
{
if (left == right)
return;
int index = Partition(a, length, left, right);
if (index > left)
QuickSort(a, length, left, index - 1);
if (index < right)
QuickSort(a, length, index + 1, right);
}

int main()
{
int a[] = { 1, 5, 6, 8, 6, 6, 2, 0, 3, 6, 9, 2, 4, 7 ,10};
QuickSort(a, 15, 0, 14);
for (int i = 0; i < 15; i++)
cout << a[i] << " ";
}