PHP单链表翻转

<?php
/**
* @file reverseLink.php
* @author showersun
* @date 2016/03/01 10:33:25
**/
class Node{
private $value;
private $next;

public function __construct($value=null){
$this->value = $value;
}
public function getValue(){
return $this->value;
}
public function setValue($value){
$this->value = $value;
}
public function getNext(){
return $this->next;
}
public function setNext($next){
$this->next = $next;
}
}
//遍历，将当前节点的下一个节点缓存后更改当前节点指针
function reverse($head){
if($head == null){
return $head;
}
$pre = $head;//注意：对象的赋值
$cur = $head->getNext();
$next = null;
while($cur != null){
$next = $cur->getNext();
$cur->setNext($pre);
$pre = $cur;
$cur = $next;
}
//将原链表的头节点的下一个节点置为null，再将反转后的头节点赋给head
$head->setNext(null);
$head = $pre;
return $head;
}
//递归，在反转当前节点之前先反转后续节点
function reverse2($head){
if (null == $head || null == $head->getNext()) {
return $head;
}
$reversedHead = reverse2($head->getNext());
$head->getNext()->setNext($head);
$head->setNext(null);
return $reversedHead;
}
function test(){
$head = new Node(0);
$tmp = null;
$cur = null;
// 构造一个长度为10的链表，保存头节点对象head
for($i=1;$i<10;$i++){
$tmp = new Node($i);
if($i == 1){
$head->setNext($tmp);
}else{
$cur->setNext($tmp);
}
$cur = $tmp;
}
//print_r($head);exit;
$tmpHead = $head;
while($tmpHead != null){
echo $tmpHead->getValue().' ';
$tmpHead = $tmpHead->getNext();
}
echo "\n";
//$head = reverse($head);
$head = reverse2($head);
while($head != null){
echo $head->getValue().' ';
$head = $head->getNext();
}
}
test();
?>