PHP 实现常用数据结构之链表

<?php
namespace App\Libraries;
class ListNode
{
    //节点数据域
    public $data;
    //节点指针域
    public $next;
    //构建节点
    public function __construct($data = null, $next = null)
    {
        $this->data = $data;
        $this->next = $next;
    }
}

<?php
namespace App\Libraries;
class SingleLinkList
{
    //头部插入建立单链表
    public function headInsert($n)
    {
        //新建头结点
        $head = new ListNode();
        for ($i=$n; $i > 0; $i--) { 
            //添加节点
            $newNode = new ListNode($i, $head->next);
            $head->next = $newNode;
        }
        return $head;
    }
    //尾部插入建立单链表
    public function tailInsert($n)
    {
        //新建头尾节点，指向同一个节点
        $head = $tail = new ListNode();
        for ($i=1; $i <= $n; $i++) { 
            //添加节点
            $newNode = new ListNode($i);
            //将尾结点指针指向新的节点
            $tail->next = $newNode;
            //将新节点标记为尾结点
            $tail = $newNode;
        }
        return $head;
    }
}

<?php
namespace App\Http\Controllers;
// use Illuminate\Http\Request;
use App\Libraries\SingleLinkList;
class IndexController extends Controller
{
    public function index ()
    {
        $list = new SingleLinkList();
        dd($list->headInsert(10));
        //dd($list->tailInsert(10));
    }
}