Iterator binary_search_helper(Iterator begin, Iterator end, const ValueType& value, Iterator not_found) {
if(begin == end) {
return not_found;
}
auto distance = std::distance(begin, end);
auto it = begin + distance/2;
if(value < *it) {
return binary_search_helper(begin, it, value, not_found);
} else if (*it < value) {
return binary_search_helper(it+1, end, value, not_found);
} else {
return it;
}
}
static int binary_search_helper(int key, int arr[], int start_index, int end_index)
{
int middle;
if (start_index > end_index) {
return -1;
}
binary_search_test_debug_stat();
middle = (start_index + end_index) / 2;
if (key == arr[middle]) {
return middle;
} else if (key < arr[middle]) {
return binary_search_helper(key, arr, start_index, middle - 1);
} else {
return binary_search_helper(key, arr, middle + 1, end_index);
}
}
static int binary_search(int key, int arr[], int length)
{
return binary_search_helper(key, arr, 0, length - 1);
}
Iterator recursive_binary_search(Iterator begin, Iterator end, const ValueType& value) {
return binary_search_helper(begin, end, value, end);
}
