<?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 = $next;
  }
}
//遍歷，將當前節(jié)點的下一個節(jié)點緩存后更改當前節(jié)點指針 
function reverse($head){
  if($head == null){
    return $head;
  }
  $pre = $head;//注意：對象的賦值
  $cur = $head->getNext();
  $next = null;
  while($cur != null){
    $next = $cur->getNext();
    $cur->setNext($pre);
    $pre = $cur;
    $cur = $next;
  }
  //將原鏈表的頭節(jié)點的下一個節(jié)點置為null，再將反轉后的頭節(jié)點賦給head 
  $head->setNext(null);
  $head = $pre;
  return $head;
}
//遞歸，在反轉當前節(jié)點之前先反轉后續(xù)節(jié)點 
function reverse2($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;
  $cur = null;
  // 構造一個長度為10的鏈表，保存頭節(jié)點對象head  
  for($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();
?>

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