leetcode\PalindromeLinkedList::isPalindrome()

Complexity

Conditions	6
Paths	12

Size

Total Lines	22
Code Lines	15

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    public static function isPalindrome(ListNode $head): bool
    {
        $fast = $head;
        $slow = $head;
        while ($fast && $fast->next) {
            $fast = $fast->next->next;
            $slow = $slow->next;
        }
        if ($fast) {
            $slow = $slow->next;
        }
        $fast = $head;
        $slow = self::helper($slow);

It seems like $slow can also be of type null; however, parameter $head of leetcode\PalindromeLinkedList::helper() does only seem to accept leetcode\util\ListNode, maybe add an additional type check?

        while ($slow) {
            if ($fast->val !== $slow->val) {
                return false;
            }
            $fast = $fast->next;
            $slow = $slow->next;
        }

        return true;
    }