C++实现快排

#include 

using namespace std;

void quickSort(int* arr, int left, int right)
{
	// 递归退出条件
	if (left >= right)
		return;

	int l = left;
	int r = right;
	int pivot = arr[l];	// 比较值，可以随机选择一个
	while (l < r)
	{
		// 从左边选择大于pivot的值
		while (arr[l] < pivot)
			l++;

		// 从右边选出小于pivot的值
		while (arr[r] > pivot)
			r--;

		// 判断是否需要交换
		if (l <= r)
		{
			int tmp = arr[l];
			arr[l] = arr[r];
			arr[r] = tmp;

			// 过滤掉当前交换值-i递增/j递减
			l++;
			r--;
		}
	}

	// 递归
	if (left < r)
		quickSort(arr, left, r);

	if (l < right)
		quickSort(arr, l, right);
}

int main(void)
{
	int arr[] = { 10, 58, 4, 47, 54, 12, 39, 65, 28, 79, 81, 26, 76, 102, 31, 46, 33, 27 };
	int len = sizeof(arr) / sizeof(arr[0]);

	cout << "排序前:" << endl;
	for (size_t i = 0; i < len; i++)
		cout << arr[i] << " ";
	cout << endl;

	quickSort(arr, 0, len - 1);

	cout << "排序后:" << endl;
	for (size_t i = 0; i < len; i++)
		cout << arr[i] << " ";
	cout << endl;

	system("pause");
	return 0;
}