/**
 * ch-ibs.c
 *   An implementation of binary search by C.H.
 */

#include "ibs.h"

int kernel(int* arr, int start, int end, int key);

int 
ibs (int* arr, int length, int key)
{
  //call the kernel
  return kernel (arr, 0, length - 1, key);
} // ibs

int 
kernel (int* arr, int start, int end, int key)
{
  //if the target is not in the array
  if (start > end)
    return -1;

  // int mid = (start + end) / 2;
  int mid = start + (end-start)/2;
  // NOT int mid = start/2 + end/2;

  //if the mid is our key
  if(arr[mid] == key)
    return mid;
  //if in the first half
  else if (arr[mid] > key)
    {
      return kernel(arr, start, mid-1, key);
    }
//if in the second half
else{
return kernel(arr, mid+1, end, key);
}
}