递归二分查找算法

#include <iostream>

using namespace std;

int recursionBinarySearch(int* arr, int num, int left, int right)
{
	if (left <= right)
	{
		int middle = (left + right) / 2;
		if (arr[middle] == num)
			return middle;
		if (arr[middle] > num)
			right = middle - 1;
		else
			left = middle + 1;

		return recursionBinarySearch(arr, num, left, right);
	}

	return -1;
}

int main(void)
{
	int num = 0;
	int arr[] = { 2, 5, 8, 13, 16, 19, 20, 33, 35, 39, 48, 51, 54, 58, 62, 64, 67, 76, 85, 98 };
	int len = sizeof(arr) / sizeof(arr[0]);

	cout << "请输入你要查找的数字：" << endl;
	cin >> num;

	int pos = recursionBinarySearch(arr, num, 0, len - 1);
	
	if (pos == -1)
		cout << "没有找到你要查找的数字" << endl;
	else
		cout << "你要查找的数字在" << pos + 1 << "的位置上" << endl;

	system("pause");
	return 0;
}