PHP implementation example of singly linked list flip operation

When a sequence contains only links pointing to its successor nodes, the linked list is called a singly linked list. This article mainly introduces the implementation of singly linked list flipping operation in PHP, and analyzes the definition, traversal, recursion, flipping and other related operation skills of PHP singly linked list in the form of examples. Friends who need it can refer to it. I hope it can help everyone.

The definition of a singly linked list and the flip operation method are given here:

<?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().&#39; &#39;;
    $tmpHead = $tmpHead->getNext();
  }
  echo "\n";
  //$head = reverse($head);
  $head = reverse2($head);
  while($head != null){
    echo $head->getValue().&#39; &#39;;
    $head = $head->getNext();
  }
}
test();
?>

Running results:

0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

Related recommendations:
Python implementation of singly linked list

PHP singly linked list flipping

php code PHP singly linked list implementation code

The above is the detailed content of PHP implementation example of singly linked list flip operation. For more information, please follow other related articles on the PHP Chinese website!