/**
 * ch-ibs.c
 *   An implementation of binary search by C.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);
}

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;

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