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LinkedList.php
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LinkedList.php
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<?php
// a LinkedList is a type of data structure
// set up the ListNode class
class ListNode
{
public $data;
public $next;
function __construct($data)
{
$this->data = $data;
$this->next = NULL;
}
function readNode()
{
return $this->data;
}
}
class LinkList
{
private $firstNode;
private $lastNode;
private $count;
function __construct()
{
$this->firstNode = NULL;
$this->lastNode = NULL;
$this->count = 0;
}
//insertion at the start of linklist
public function insertFirst($data)
{
$link = new ListNode($data);
$link->next = $this->firstNode;
$this->firstNode = &$link;
/* If this is the first node inserted in the list
then set the lastNode pointer to it.
*/
if($this->lastNode == NULL)
$this->lastNode = &$link;
$this->count++;
}
//displaying all nodes of linklist
public function readList()
{
$listData = array();
$current = $this->firstNode;
while($current != NULL)
{
array_push($listData, $current->readNode());
$current = $current->next;
}
foreach($listData as $v){
echo $v." ";
}
}
//reversing all nodes of linklist
public function reverseList()
{
if($this->firstNode != NULL)
{
if($this->firstNode->next != NULL)
{
$current = $this->firstNode;
$new = NULL;
while ($current != NULL)
{
$temp = $current->next;
$current->next = $new;
$new = $current;
$current = $temp;
}
$this->firstNode = $new;
}
}
}
//deleting a node from linklist $key is the value you want to delete
public function deleteNode($key)
{
$current = $this->firstNode;
$previous = $this->firstNode;
while($current->data != $key)
{
if($current->next == NULL)
return NULL;
else
{
$previous = $current;
$current = $current->next;
}
}
if($current == $this->firstNode)
{
if($this->count == 1)
{
$this->lastNode = $this->firstNode;
}
$this->firstNode = $this->firstNode->next;
}
else
{
if($this->lastNode == $current)
{
$this->lastNode = $previous;
}
$previous->next = $current->next;
}
$this->count--;
}
//empty linklist
public function emptyList()
{
$this->firstNode == NULL;
}
//insertion at index
public function insert($NewItem,$key){
if($key == 0){
$this->insertFirst($NewItem);
}
else{
$link = new ListNode($NewItem);
$current = $this->firstNode;
$previous = $this->firstNode;
for($i=0;$i<$key;$i++)
{
$previous = $current;
$current = $current->next;
}
$previous->next = $link;
$link->next = $current;
$this->count++;
}
}
}
$obj = new LinkList();
$obj->insertFirst($value);
$obj->insert($value,$key); // at any index
$obj->deleteNode($value);
$obj->readList();