递归法

c++
#include <iostream>

using namespace std;

int binarySearch(int* nums, int target, int left, int right)
{
	//二分查找
	if(left>right) return -1;
	int mid = (left+right)/2;
	if(nums[mid] == target) return mid;
	if(nums[mid] < target) return binarySearch(nums, target, mid+1, right);
	if(nums[mid] > target) return binarySearch(nums, target, left, mid-1);
}
int search(int* nums, int numSize, int target)
{
	return binarySearch(nums, target, 0, numSize-1);
}

int main()
{
	int nums[7] = {-1 ,2, 5, 6, 7, 8, 9};
	int index = search(nums, 7, 5);
	cout<<index<<endl;
	return 0;
}