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PalindromeLinkedList::isPalindrome2()   A
last analyzed

↳ Parent: PalindromeLinkedList

Complexity

Conditions 6
Paths 6

Size

Total Lines 16
Code Lines 10

Duplication

Lines 0
Ratio 0 %

Importance

Changes 1
Bugs 0 Features 0
Metric Value
eloc 10
c 1
b 0
f 0
dl 0
loc 16
rs 9.2222
cc 6
nc 6
nop 1
1 
<?php
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declare(strict_types=1);

            


            
                                                                                                            
                            
            
                                    
            
            

                
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namespace leetcode;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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use leetcode\util\ListNode;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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class PalindromeLinkedList

            


            
                                                                                                            
                            
            
                                    
            
            

                
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{

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    public static function isPalindrome(ListNode $head): bool

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        $fast = $head;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        $slow = $head;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        while ($fast && $fast->next) {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $fast = $fast->next->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $slow = $slow->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        if ($fast) {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $slow = $slow->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        $fast = $head;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        $slow = self::helper($slow);

            


                            

                    
                        
                    
                    
                    
                    
                                                                                                    
                        

                            
                            
0 ignored issues

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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?
                                                                                                                                                                                           (
                                     Ignorable by Annotation
                                )
                                

                                    
 If this is a false-positive, you can also ignore this issue in your code via the ignore-type   annotation

                                    

                                        

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        $slow = self::helper(/** @scrutinizer ignore-type */ $slow);

                                        

                                                                            

                                

                                                                                                                                                                                                                                                                                        

                    
                                                    

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        while ($slow) {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            if ($fast->val !== $slow->val) {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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                return false;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $fast = $fast->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $slow = $slow->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        return true;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    /**

            


            
                                                                                                            
                            
            
                                    
            
            

                
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     * Note: Time Limit Exceeded.

            


            
                                                                                                            
                            
            
                                    
            
            

                
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     *

            


            
                                                                                                            
                            
            
                                    
            
            

                
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     * @param \leetcode\util\ListNode $head

            


            
                                                                                                            
                            
            
                                    
            
            

                
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     *

            


            
                                                                                                            
                            
            
                                    
            
            

                
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     * @return bool

            


            
                                                                                                            
                                                                
            
                                    
            
            

                
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     */

            


            
                                                                        
                            
            
                                    
            
            

                
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    public static function isPalindrome2(ListNode $head): bool

            


            
                                                                        
                            
            
                                    
            
            

                
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    {

            


            
                                                                        
                            
            
                                    
            
            

                
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        $node = $head;

            


            
                                                                        
                            
            
                                    
            
            

                
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        $queue = [];

            


            
                                                                        
                            
            
                                    
            
            

                
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        while ($node) {

            


            
                                                                        
                            
            
                                    
            
            

                
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            array_push($queue, $node);

            


            
                                                                        
                            
            
                                    
            
            

                
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            $node = $node->next;

            


            
                                                                        
                            
            
                                    
            
            

                
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        }

            


            
                                                                        
                            
            
                                    
            
            

                
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        while (count($queue) >= 2) {

            


            
                                                                        
                            
            
                                    
            
            

                
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            [$p, $q] = [array_shift($queue), array_pop($queue)];

            


            
                                                                        
                            
            
                                    
            
            

                
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            if ($p && $q && $p->val != $q->val) {

            


            
                                                                        
                            
            
                                    
            
            

                
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                return false;

            


            
                                                                        
                            
            
                                    
            
            

                
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            }

            


            
                                                                        
                            
            
                                    
            
            

                
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        }

            


            
                                                                        
                            
            
                                    
            
            

                
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        return true;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    private static function helper(ListNode $head): ?ListNode

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        $prev = null;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        while ($head) {

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $next = $head->next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $head->next = $prev;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $prev = $head;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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            $head = $next;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        }

            


            
                                                                                                            
                            
            
                                    
            
            

                
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        return $prev;

            


            
                                                                                                            
                            
            
                                    
            
            

                
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    }

            


            
                                                                                                            
                                                                
            
                                    
            
            

                
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}

            


            
                                                        
            
                                    
            
            

                
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