快速排序

功力不够，准确快速实现一个快速排序不容易，关键是那些边界的>=和>一下子控制不好。

void quickSort(int a[], int l, int r)
{
	int lKeeper = l;
	int rKeeper = r;
	int key = a[l];
	int keyIndex = l;
	if (lKeeper >= rKeeper)
		return;
	while (l < r)
	{
		while (a[r] >= key && r > l)
			--r;
		if (l != r)
		{
			swap(a[l], a[r]);
			keyIndex = r;
		}
		while (a[l] <= key && l < r)
			++l;
		if (l != r)
		{
			swap(a[l], a[r]);
			keyIndex = l;
		}
	}
	quickSort(a, lKeeper, keyIndex - 1);
	quickSort(a, keyIndex + 1, rKeeper);
}