<?php

class ListNode {

public $val = 0;

public $next = null;

function __construct($val = 0, $next = null) {

$this->val = $val;

$this->next = $next;

}

}

/**

* @param ListNode $head

* @param Integer $k

* @return ListNode

*/

function getKthFromEnd($head, $k) {

if($head === null || $head->next === null){

return null;

}

$cur = $head;

$count = 0;

while ($cur != null){

$cur = $cur->next;

$count++;

}

if($k > $count){

return null;

}

$break_num = $count - $k;

$cur = $head;

while ($cur != null){

if($break_num == 0){

return $cur;

}

$break_num--;

$cur = $cur->next;

}

}