binarySearch 只有10%程序员能正确实现二分查找算法

#include <iostream>
#include <algorithm>
using namespace std;
int binary_search(int * num, int begin, int end, int target)
//对num[begin, end] 进行二分查找。 找到返回位置， 否则返回-1
{
int i = begin;
int j = end;
int middle;
while (i <= j)
{
middle = i + (j - i) / 2;
if (num[middle] > target)
{
j = middle - 1;
}
else
if (num[middle] < target)
{
i = middle + 1;
}
else
{
return middle;
}
}
return -1;
}
int num[10] = {1,3,5,6,8,9,10,13,15,19};
int main()
{
printf("%d/n", binary_search(num, 0, 9, 1) );
printf("%d/n", binary_search(num, 0, 9, 2) );
printf("%d/n", binary_search(num, 0, 9, 3) );
printf("%d/n", binary_search(num, 0, 9, 4) );
printf("%d/n", binary_search(num, 0, 9, 5) );
printf("%d/n", binary_search(num, 0, 9, 6) );
printf("%d/n", binary_search(num, 0, 9, 7) );
printf("%d/n", binary_search(num, 0, 9, 8) );
printf("%d/n", binary_search(num, 0, 9, 9) );
printf("%d/n", binary_search(num, 0, 9, 10) );
printf("%d/n", binary_search(num, 0, 9, 11) );
printf("%d/n", binary_search(num, 0, 9, 12) );
printf("%d/n", binary_search(num, 0, 9, 13) );
printf("%d/n", binary_search(num, 0, 9, 14) );
printf("%d/n", binary_search(num, 0, 9, 15) );
printf("%d/n", binary_search(num, 0, 9, 16) );
printf("%d/n", binary_search(num, 0, 9, 17) );
printf("%d/n", binary_search(num, 0, 9, 18) );
printf("%d/n", binary_search(num, 0, 9, 19) );
printf("%d/n", binary_search(num, 0, 9, 20) );
printf("%d/n", binary_search(num, 5, 9, 17) );
}

只有10%程序员能正确实现二分查找算法