PHP 7 Data Structures and Algorithms

Building circular linked list

Building a circular linked list is not at as hard as it sounds from the name. So far, we have seen that adding a new node at the end is pretty simple; we set the next reference of the last node to NULL. In a circular linked list, the last node's next reference will actually point to the first node, thereby creating a circular list. Let's write a simple circular linked list where the nodes will be inserted at the end of the list:

class CircularLinkedList {     private $_firstNode = NULL;     private $_totalNode = 0;     public function insertAtEnd(string $data = NULL) {         $newNode = new ListNode($data);         if ($this->_firstNode === NULL) {             $this->_firstNode = &$newNode;         } else {             $currentNode = $this->_firstNode;  while ...