[Algorithm] - 이진 탐색(Binary Search)

#include <iostream>
using std::cout;
using std::endl;

int BinarySearch(int arr[], int len, int target) 
{ 
    int first = 0; 
    int last = len - 1; 
    int mid; 
    
    while (first <= last) 
    { 
    	mid = (first + last) ⁄ 2; 
        if (target == arr[mid]) 
        { 
        	return mid; 
        } 
        else 
        { 
        	if (target < arr[mid]) 
            { 
            	last = mid - 1; 
            } 
            else 
            { 
                first = mid + 1; 
            } 
        } 
    } 
    
    return -1; 
} 

int main(void) 
{ 
    int arr[] = { 1, 3, 5, 7, 9 }; 
    int index = BinarySearch(arr, sizeof(arr) ⁄ sizeof(arr[0]), 7); 
    
    if (index == -1) 
    { 
        cout << "Search Failed" << endl; 
    } 
    else 
    { 
        cout << "Target Save Index : " << index << endl; 
    } 
    
    index = BinarySearch(arr, sizeof(arr) ⁄ sizeof(arr[0]), 4); 
    
    if (index == -1) 
    { 
        cout << "Search Failed" << endl; 
    } 
    else 
    { 
        cout << "Target Save Index : " << index << endl; 
    } 
}