<查找算法> 二分查找BinarySearch

#include<iostream>
using namespace std;

int BinarySearch(int arr[],int begin,int end,int num)
{
    if(arr == NULL || begin < 0 || end < 0 || begin >= end) return -1;

    int mid = (begin+end)/2;
    if(arr[mid] == num) 
        return mid;
    else if(arr[mid] > num)
        BinarySearch(arr,begin,mid-1,num);
    else if(arr[mid] < num)
        BinarySearch(arr,mid+1,end,num);
}

int main()
{
    int arr[] = {2,4,11,13,20,24,33,56,78,91};
    cout << "找到num在数组中的下标为：" << BinarySearch(arr,0,sizeof(arr)/sizeof(arr[0])-1,78);

    system("pause");
    return 0;
}