查找算法之二分查找

二分查找的代碼如下:

#include <iostream>
using namespace std;

long BinarySearch(int a[], int begin, int end, int elem)
{
	if(begin > end)
		return -1;
	int mid = (begin + end) / 2;
	//int mid = begin + (end - begin + 1) / 2 - 1;
	if(a[mid] == elem)
		return mid;
	else if(a[mid] > elem)
		return BinarySearch(a, begin, mid - 1, elem);
	else
		return BinarySearch(a, mid + 1, end, elem);
}

int main()
{
	int a[] = {1, 2, 3, 4, 5, 6, 7, 8};
	int len = sizeof(a)/sizeof(int);
	//cout<< BinarySearch(a, 0, len - 1, 6);
	cout<< BinarySearch(a, 0, len - 1, 6);
	return 0;
}