unsigned int BinaryHeap::insert(const unsigned int item, const int key) {
_items.push_back(HeapItem(item, key, _binaryHeap.size()));
_binaryHeap.push_back(_items.size() - 1);
HeapItem &result = _items.at(_binaryHeap.back());
this->_siftUp(result);
return _items.size() - 1;
}
// Helper function that searches the tree
void search(Node* node, const T& target, int k, std::priority_queue<HeapItem>& heap)
{
if(node == NULL) return; // indicates that we're done here
// Compute distance between target and current node
ScalarType dist = distance(_items[node->index], target);
// If current node within radius tau
if(dist < _tau) {
if(heap.size() == static_cast<size_t>(k)) heap.pop(); // remove furthest node from result list (if we already have k results)
heap.push(HeapItem(node->index, dist)); // add current node to result list
if(heap.size() == static_cast<size_t>(k)) _tau = heap.top().dist; // update value of tau (farthest point in result list)
}
// Return if we arrived at a leaf
if(node->left == NULL && node->right == NULL) {
return;
}
// If the target lies within the radius of ball
if(dist < node->threshold) {
if(dist - _tau <= node->threshold) { // if there can still be neighbors inside the ball, recursively search left child first
search(node->left, target, k, heap);
}
if(dist + _tau >= node->threshold) { // if there can still be neighbors outside the ball, recursively search right child
search(node->right, target, k, heap);
}
// If the target lies outsize the radius of the ball
} else {
if(dist + _tau >= node->threshold) { // if there can still be neighbors outside the ball, recursively search right child first
search(node->right, target, k, heap);
}
if (dist - _tau <= node->threshold) { // if there can still be neighbors inside the ball, recursively search left child
search(node->left, target, k, heap);
}
}
}
