Basic operations in Singly Linked List In PHP

basic-operations-in-singly-linked-list-in-php.php

<?php

class Node
{
    public $value;
    public $next;

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

class LinkedList
{
    public $head;
    public $tail;
    public $length;

    public function __construct(public int $value)
    {
        $newNode = new Node($value);
        $this->head = $newNode;
        $this->tail = $newNode;
        $this->length = 1;
    }

    public function append($value)
    {
        $newNode = new Node($value);
        if ($this->length == 0) {
            $this->head = $newNode;
            $this->tail = $newNode;
        } else {
            $this->tail->next = $newNode;
            $this->tail = $newNode;
        }
        $this->length++;
    }

    public function getNode($index)
    {
        if ($index < 0 || $index >= $this->length) {
            return null;
        }
        $temp = $this->head;
        for ($i = 0; $i < $index; $i++) {
            $temp = $temp->next;
        }
        return $temp;
    }

    public function setNode($index, $value)
    {
        $temp = $this->getNode($index);
        if ($temp) {
            $temp->value = $value;
        }
    }

    public function prepend($value)
    {
        $newNode = new Node($value);
        if ($this->length == 0) {
            $this->head = $newNode;
            $this->tail = $newNode;
        } else {
            $newNode->next = $this->head;
            $this->head = $newNode;
        }
        $this->length++;
    }

    public function insert($index, $value)
    {
        if ($index < 0 || $index >= $this->length) {
            return null;
        }
        if ($index == 0) {
            $this->prepend($value);
            return;
        } elseif ($index == $this->length) {
            $this->append($value);
            return;
        }
        $newNode = new Node($value);
        $temp = $this->getNode($index - 1);
        $newNode->next = $temp->next;
        $temp->next = $newNode;
        $this->length++;
    }

    public function popFirst()
    {
        if ($this->length == 0) {
            return null;
        }
        if ($this->length == 1) {
            $this->head = null;
            $this->tail = null;
        } else {
            $temp = $this->head;
            $this->head = $temp->next;
            $temp->next = null;
        }
        $this->length--;
    }

    public function pop()
    {
        if ($this->length == 0) {
            return null;
        }

        if ($this->length == 1) {
            $this->head = null;
            $this->tail = null;
        } else {
            $temp = $this->head;
            $prev = $this->head;
            while ($temp->next) {
                $prev = $temp;
                $temp = $temp->next;
            }
            $this->tail = $prev;
            $this->tail->next = null;
        }
        $this->length--;
    }

    public function remove($index)
    {
        if ($index < 0 || $index >= $this->length) {
            return null;
        }
        if ($index == 0) {
            return $this->popFirst();
        } elseif ($index == $this->length - 1) {
            return $this->pop();
        }
        $temp = $this->getNode($index - 1);
        $temp->next = $temp->next->next;
        $this->length--;
    }

    public function printAll()
    {
        $temp = $this->head;
        while ($temp != null) {
            echo $temp->value . '->';
            $temp = $temp->next;
        }
        echo PHP_EOL;
    }
}

$ll = new LinkedList(1);
$ll->append(22);
$ll->append(7);

// Get Node
// $ll->getNode(0);

// Set Node
// $ll->setNode(1,33);

// Prepend Node
// $ll->prepend(13);

// Insert Node
// $ll->insert(1,13);

// Pop First
// $ll->popFirst();

// Pop Last
// $ll->pop();

$ll->printAll();