二分查找算法

实现：

/**********************************************
二分查找算法
by Rowandjj
2014/7/11
**********************************************/
#include<iostream>
using namespace std;
//二分查找算法,arr为待查数组，len为数组长度，target为待查元素
int binary_search(int arr[],int len,int target);
int main()
{
	int t;
	int arr[] = {-3,0,3,4,5,36,40,57,78,90};
	int arr2[] = {-3,0,3,11};
	cin>>t;
	cout<<binary_search(arr2,5,t)<<endl;
	return 0;
}
//确保数组有序且按非降序排列
int binary_search(int arr[],int len,int target)
{
	int low = 0,high = len-1,middle;
	while(low <= high)
	{
		middle = low + ((high - low)>>1);//防溢出且高效.不推荐用middle = (high + low)/2
		if(arr[middle] == target)
		{
			return middle;
		}else if(arr[middle] > target)//去前半部分找
		{
			high = middle - 1;
		}else//arr[middle] < target,去后半部分找
		{
			low = middle + 1;
		}
	}
	return -1;
}

二分查找算法,布布扣,bubuko.com

二分查找算法

原文：http://blog.csdn.net/chdjj/article/details/37692781