用PHP实现的单链表

来源：互联网发布：冰球打架规则知乎编辑：程序博客网时间：2024/06/08 09:51

单链表顾名思义就是一个链式数据结构，它有一个表头，并且除了最后一个节点外，所有节点都有其后继节点。如下图。

首先，我们写出链表节点的类。单链表中的每一个节点，都保存其数据域和后驱指针

//链表节点 class node {     public $id; //节点id     public $name; //节点名称     public $next; //下一节点        public function __construct($id, $name) {         $this->id = $id;         $this->name = $name;         $this->next = null;     } }

链表中还有两个特别重要的方法，插入和删除。插入需要找到插入的位置，把前一个元素的next指针指向被插入的节点，并将被插入节点的next指针指向后一个节点，如下图左侧所示。而删除则是把前一个节点的next指针指向后一个节点，并返回被删除元素的数据内容，如下图右侧所示。

//单链表 class singelLinkList {     private $header; //链表头节点        //构造方法     public function __construct($id = null, $name = null) {         $this->header = new node ( $id, $name, null );     }     //获取链表长度     public function getLinkLength() {         $i = 0;         $current = $this->header;         while ( $current->next != null ) {             $i ++;             $current = $current->next;         }         return $i;     }     //添加节点数据     public function addLink($node) {         $current = $this->header;         while ( $current->next != null ) {             if ($current->next->id > $node->id) {                 break;             }             $current = $current->next;         }         $node->next = $current->next;         $current->next = $node;     }     //删除链表节点     public function delLink($id) {         $current = $this->header;         $flag = false;         while ( $current->next != null ) {             if ($current->next->id == $id) {                 $flag = true;                 break;             }             $current = $current->next;         }         if ($flag) {             $current->next = $current->next->next;         } else {             echo "未找到id=" . $id . "的节点！<br>";         }     }    //判断连表是否为空    public function isEmpty(){            return $this->header == null;    }    //清空链表    public function clear(){            $this->header = null;    }     //获取链表     public function getLinkList() {         $current = $this->header;         if ($current->next == null) {             echo ("链表为空!");             return;         }         while ( $current->next != null ) {             echo 'id:' . $current->next->id . '   name:' . $current->next->name . "<br>";             if ($current->next->next == null) {                 break;             }             $current = $current->next;         }     }     //获取节点名字     public function getLinkNameById($id) {         $current = $this->header;         if ($current->next == null) {             echo "链表为空!";             return;         }         while ( $current->next != null ) {             if ($current->id == $id) {                 break;             }             $current = $current->next;         }         return $current->name;     }     //更新节点名称     public function updateLink($id, $name) {         $current = $this->header;         if ($current->next == null) {             echo "链表为空!";             return;         }         while ( $current->next != null ) {             if ($current->id == $id) {                 break;             }             $current = $current->next;         }         return $current->name = $name;     } }$lists = new singelLinkList (); $lists->addLink ( new node ( 5, 'eeeeee' ) ); $lists->addLink ( new node ( 1, 'aaaaaa' ) ); $lists->addLink ( new node ( 6, 'ffffff' ) ); $lists->addLink ( new node ( 4, 'dddddd' ) ); $lists->addLink ( new node ( 3, 'cccccc' ) ); $lists->addLink ( new node ( 2, 'bbbbbb' ) ); $lists->getLinkList (); echo "<br>-----------删除节点--------------<br>"; $lists->delLink ( 5 ); $lists->getLinkList ();echo "<br>-----------更新节点名称--------------<br>"; $lists->updateLink ( 3, "222222" ); $lists->getLinkList ();echo "<br>-----------获取节点名称--------------<br>"; echo $lists->getLinkNameById ( 5 );echo "<br>-----------获取链表长度--------------<br>"; echo $lists->getLinkLength ();

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