public static function findSuccessor(BinaryTreeNodeWithParent $node)
{
$right = $node->getRight();
if ($right !== null) {
return self::diveDownAndLeft($right);
}
$rightMostParent = self::climbUpAndRight($node);
// The parent of rightMostParent must be a left parent or null
// because we climbed as far right as possible
return $rightMostParent->getParent();
}
public function getRandomNode()
{
$left = parent::getLeft();
$right = parent::getRight();
$leftNodeCount = $left !== null ? $left->getNodeCount() : 0;
$rightNodeCount = $right !== null ? $right->getNodeCount() : 0;
$random = mt_rand(-$leftNodeCount, $rightNodeCount);
if ($random < 0) {
return $left->getRandomNode();
} elseif ($random > 0) {
return $right->getRandomNode();
}
// $random == 0
return $this;
}
