leetcode\LinkedListCycleII::detectCycle()

Complexity

Conditions	6
Paths	5

Size

Total Lines	20
Code Lines	13

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    public static function detectCycle(?ListNode $head): ?ListNode
    {
        if (!$head) {
            return null;
        }
        $slow = $fast = $head;
        while ($fast->next && $fast->next->next) {
            $slow = $slow->next;
            $fast = $fast->next->next;
            if ($slow === $fast) {
                $curr = $head;
                while ($curr !== $slow) {
                    $curr = $curr->next;
                    $slow = $slow->next;
                }
                return $slow;
            }
        }

        return null;
    }