Singly Linked List

example.php

<?php

use DataStructures\LinkedList;

$linkedList = new LinkedList();

$linkedList->inserFirst(10);
$linkedList->inserFirst(20);
$linkedList->insertLast(40);
$linkedList->insertLast(30);

node.php

<?php

namespace DataStructures;

class Node
{
  public $value = null;
  public $next = null;

  public function __construct($data)
  {
    $this->value = $data;
  }

  public function readNode()
  {
    return $this->value;
  }
}

sample.json

{
  "firstNode": {
    "value": 20,
    "next": {
      "value": 10,
      "next": {
        "value": 40,
        "next": {
          "value": 30,
          "next": null
        }
      }
    }
  },
  "lastNode": {
    "value": 30,
    "next": null
  },
  "count": 4
}

singly-linked-list.php

<?php

namespace DataStructures;

use DataStructures\Node;

class LinkedList
{
  /**
   * make as public to print in json
   */
  public $firstNode = null;
  public $lastNode = null;
  public $count = 0;

  public function inserFirst($data)
  {
    if ($this->firstNode !== null) {
      $node = $this->getNewNode($data);
      $node->next = $this->firstNode;
      $this->firstNode = &$node;
      $this->count++;
    } else {
      $this->insertFirstNode($data);
    }
  }

  public function insertLast($data)
  {
    if ($this->firstNode !== null) {
      $node = $this->getNewNode($data);

      $this->lastNode->next = $node;
      $this->lastNode = &$node;
      $this->count++;
    } else {
      $this->insertFirstNode($data);
    }
  }

  private function insertFirstNode($data)
  {
    $node = $this->getNewNode($data);

    $this->firstNode = &$node;
    $this->lastNode = &$node;
    $this->count++;
  }

  public function getCount()
  {
    return $this->count;
  }

  private function getNewNode($data)
  {
    return new Node($data);
  }
}