算法 二分查找 (C++)

二分查找的实现：

 #include <iostream>  
  
using namespace std;  
  
/* 
*二分查找思想：1、数组从小到大排序；2、查找的key每次和中间数比较，如果key小于mid 
查找mid左侧的数组部分；如果key大于mid，则查找mid右侧的数组部分；如果相等，则直接返回mid。 
 
输入：排序数组-array,数组大小-aSize,查找值-key 
返回：返回数组中的相应位置，否则返回-1 
*/  
//非递归查找  
int BinarySearch(int *array, int aSize, int key)  
{  
    if ( array == NULL || aSize == 0 )  
        return -1;  
    int low = 0;  
    int high = aSize - 1;  
    int mid = 0;  
  
    while ( low <= high )  
    {  
        mid = (low + high )/2;  
          
        if ( array[mid] < key)  
            low = mid + 1;  
        else if ( array[mid] > key )     
            high = mid - 1;  
        else  
            return mid;  
    }  
    return -1;  
}  
//递归  
int BinarySearchRecursive(int *array, int low, int high, int key)  
{  
    if ( low > high )  
        return -1;  
    int mid = ( low + high )/2;  
      
    if ( array[mid] == key )  
        return mid;  
    else if ( array[mid] < key )  
        return BinarySearchRecursive(array, mid+1, high, key);  
    else  
        return BinarySearchRecursive(array, low, mid-1, key);  
}  
  
int main()  
{  
    int array[10];  
    for (int i=0; i<10; i++)  
        array[i] = i;  
  
    cout<<"No recursive:"<<endl;  
    cout<<"position:"<<BinarySearch(array, 10, 6)<<endl;  
    cout<<"recursive:"<<endl;  
    cout<<"position:"<<BinarySearchRecursive(array, 0, 9, 6)<<endl;  
  
    return 0;  
}