Leetcode linked list detect cycle – PHP

I am looking to find a way to detect cycle in linked list using Array in PHP. Please note I am aware of two pointer approach but I am keen on understanding approach if it is feasible to achieve this with php array.

in Java code sample on leetcode is as below:

public boolean hasCycle(ListNode head) {
    Set<ListNode> nodesSeen = new HashSet<>();
    while (head != null) {
        if (nodesSeen.contains(head)) {
            return true;
        } else {
            nodesSeen.add(head);
        }
        head = head.next;
    }
    return false;
}

Answer

Based on the given info I would rewrite it like this utilizing also an array as hashmap for visited nodes.

function hasCycle(SplDoublyLinkedList $list): bool
{
    $nodesSeen = [];
    $list->rewind();
    while ($current = $list->current()) {
        if (isset($nodesSeen[$current]))
          return true;
        $nodesSeen[$current] = true;
        $list->next();
    }
    return false;
}

Testing with having a cycle on a.

$list = new SplDoublyLinkedList();
$list->push('a');
$list->push('b');
$list->push('c');
$list->push('a');
var_dump(hasCycle($list));

true

Testing with having no cycle.

$list = new SplDoublyLinkedList();
$list->push('a');
$list->push('b');
$list->push('c');
$list->push('d');
var_dump(hasCycle($list));

false