/* Returns the height of the bottom of the given tower NODE.
The performance of this function is O(lg n) in the number of
nodes in the tower. It is often possible to avoid calling
this function, either by taking advantage of the NODE_START
parameter to tower_lookup or by incrementally keeping track of
height while iterating through a tower. In the former case
the asymptotic performance is no different, since tower_lookup
is also O(lg n), but in the latter case performance improves
from O(lg n) to O(1). */
unsigned long int
tower_node_get_level (const struct tower_node *node)
{
const struct abt_node *p = &node->abt_node;
unsigned long level = get_subtree_size (p->down[0]);
while (p->up != NULL)
{
if (p == p->up->down[1])
level += (get_subtree_size (p->up->down[0])
+ abt_to_tower_node (p->up)->size);
p = p->up;
}
return level;
}
KMPoint KMCentersNodeSplit::sample_center() {
int r = internal::random_int(get_subtree_size());
if (r == 0) { // sample from this node
KMRectangle exp_box = bnd_box_.expand(3); // compute 3x expanded box
return exp_box.sample();
} else if (r <= children_[0]->get_subtree_size()) { // sample from left
return children_[0]->sample_center();
} else { // sample from right subtree
return children_[1]->sample_center();
}
}
/* Returns the total height of tower T. */
unsigned long
tower_height (const struct tower *t)
{
return get_subtree_size (t->abt.root);
}
