php链表操作

1.

<?php//单链表 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;       }   }  class singelNodeList {       private $header; //链表头节点        public function __construct($id = null, $name = null) {   //构造方法           $this->header = new node ( $id, $name, null );       }          //获取链表长度       public function getNodeLength() {           $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！
";           }       }         //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 getNodeList() {           $current = $this->header;           if ($current->next == null) {               echo ("链表为空!");               return;           }           while ( $current->next != null ) {               echo 'id:' . $current->next->id . '   name:' . $current->next->name . "
";               if ($current->next->next == null) {                   break;               }               $current = $current->next;           }       }          //获取节点名字       public function getNodeNameById($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 $current->name;       }          //更新节点名称       public function updateNode($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;       }  // function eatList(Node $node){ function eatList($this->header){     $fast = $slow = $node;    $first_target = null;    if($node->data == null) {        return false;    }    while (true) {        if($fast->next != null && $fast->next->next != null) {            $fast = $fast->next->next;      // 快指针一次走两步            $slow = $slow->next;            // 慢指针一次走一步        } else {            return false;        }        if($fast == $slow) {                // 慢指针追上快指针,说明有环            $p1 = $node;                    // p1指针指向head节点,p2指针指向它们第一次相交的点,                                         // 然后两个指针每次移动一步,当它们再次相交,即为 环的入口            $p2 = $fast;            while($p1 != $p2) {                $p1 = $p1->next;                $p2 = $p2->next;            }            return $p1;                     // 环的入口节点$        }     }}}  $lists = new singelNodeList ();   $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->addLink ( new node ( 4, 'bbbbbb' ) );  $lists->addLink ( new node ( 3, 'bbbbbb' ) );  $lists->addLink ( new node ( 2, 'bbbbbb' ) );  print_r($this->eatList($list));// $lists->delLink ( 5 );    //删除节点5$lists->getNodeList ();   $lists->updateNode ( 3, "222222" );    //更新节点名称// $lists->getNodeList ();  echo $lists->getNodeNameById ( 5 );  //获取节点名称echo $lists->getNodeLength (); //获取链表长度