-
- /**
- * **Double linked list
- * @author zhiyuan12@
- * @modified 2012-10-25
- * @site: bbs.it-home.org
- */
- /**
- * Linked list element node class
- */
- class Node_Element {
- public $pre = NULL; // Precursor
- public $next = NULL; // Successor
- public $key = NULL; // Element key value
- public $data = NULL; // Node value
- function __Construct($key, $data) {
- $this->key = $key;
- $this ->data = $data;
- }
- }
- /**
- * Doubly linked list class
- */
- class DoubleLinkedList {
- private $head; // Head pointer
- private $tail; // Tail pointer
- private $current; // Current pointer
- private $len; // Linked list length
- function __Construct() {
- $this->head = self::_getNode ( null, null );
- $this->curelement = $this->head;
- $this->tail = $this->head;
- $len = 0;
- }
- /**
- * @ desc: Read all nodes of the linked list
- */
- public function readAll() {
- $tmp = $this->head;
- while ( $tmp->next !== null ) {
- $tmp = $tmp->next;
- var_dump ( $tmp->key, $tmp->data );
- }
- }
- public function move($pos1, $pos2) {
- $pos1Node = $this->findPosition ( $pos1 );
- $pos2Node = $this->findPosition ( $pos2 );
- if ($pos1Node !== null && $pos2Node !== null) {
- $tmpKey = $pos1Node->key;
- $tmpData = $pos1Node->data;
- $pos1Node->key = $pos2Node->key;
- $pos1Node-> ;data = $pos2Node->data;
- $pos2Node->key = $tmpKey;
- $pos2Node->data = $tmpData;
- return true;
- }
- return false;
- }
- /**
- * @ desc: Delete the node at the specified keyword
- *
- * @param: $key
- * The linked list element key at the specified position
- */
- public function delete($key) {
- $pos = $this->find ( $key );
- if ($pos !== null) {
- $tmp = $pos;
- $last = null ;
- $first = true;
- while ( $tmp->next !== null && $tmp->next->key === $key ) {
- $tmp = $tmp->next;
- if (! $first) {
- $this->delNode ( $last );
- } else {
- $first = false;
- }
- $last = $tmp;
- }
- if ($tmp->next ! == null) {
- $pos->pre->next = $tmp->next;
- $tmp->next->pre = $pos->pre;
- } else {
- $pos ->pre->next = null;
- }
- $this->delNode ( $pos );
- $this->delNode ( $tmp );
- }
- }
- /**
- * @ desc: Delete the node at the specified position
- *
- * @param: $key
- * The key of the linked list element at the specified position
- */
- public function deletePosition($pos) {
- $tmp = $this->findPosition ( $pos );
- if ($tmp === null) {
- return true;
- }
- if ($tmp === $ this->getTail ()) {
- $tmp->pre->next = null;
- $this->delNode ( $tmp );
- return true;
- }
- $tmp->pre-> ;next = $tmp->next;
- $tmp->next->pre = $tmp->pre;
- $this->delNode ( $tmp );
- }
- /**
- * @ desc: Insert the node before the specified key value
- *
- * @param : $key
- * //The linked list element key at the specified position
- * @param : $data
- * //The linked list element data to be inserted
- * @param: $flag
- * //Whether to search for positions sequentially for insertion
- */
- public function insert($key, $data, $flag = true) {
- $newNode = self::_getNode ( $key, $data );
- $tmp = $this->find ( $key, $ flag );
- if ($tmp !== null) {
- $newNode->pre = $tmp->pre;
- $newNode->next = $tmp;
- $tmp->pre = $newNode ;
- $newNode->pre->next = $newNode;
- }else {
- $newNode->pre = $this->tail;
- $this->tail->next = $newNode;
- $this->tail = $newNode;
- }
- $this->len ++;
- }
- /**
- * @ desc: Insert the node before the specified position
- *
- * @param : $pos
- * Specify the position to insert into the linked list
- * @param : $key
- * The key of the linked list element at the specified position
- * @param : $data
- * Linked list element data to be inserted
- */
- public function insertPosition($pos, $key, $data) {
- $newNode = self::_getNode ( $key, $data );
- $tmp = $this->findPosition ( $pos );
- if ($tmp !== null) {
- $newNode->pre = $tmp->pre;
- $newNode->next = $tmp;
- $tmp->pre = $newNode;
- $newNode->pre->next = $newNode;
- } else {
- $newNode->pre = $this->tail;
- $this->tail->next = $newNode;
- $this->tail = $newNode;
- }
- $this->len ++;
- return true;
- }
- /**
- * @desc: Query the specified position data based on the key value
- *
- * @param : $key
- * //The linked list element key at the specified position
- * @param : $flag
- * //Whether to search in order
- */
- public function find($key, $flag = true) {
- if ($flag) {
- $tmp = $this->head;
- while ( $tmp->next !== null ) {
- $tmp = $tmp->next;
- if ($tmp->key === $key) {
- return $tmp;
- }
- }
- } else {
- $tmp = $this->getTail ();
- while ( $tmp->pre !== null ) {
- if ($tmp->key === $key) {
- return $tmp;
- }
- $tmp = $tmp->pre;
- }
- }
- return null;
- }
- /**
- * @ desc: Query the specified location data based on the location
- *
- * @param: $pos
- * //The linked list element key at the specified location
- */
- public function findPosition($pos) {
- if ($pos <= 0 || $pos > $this->len)
- return null;
- if ($pos < ($this->len / 2 + 1)) {
- $tmp = $this->head;
- $count = 0;
- while ( $tmp->next !== null ) {
- $tmp = $tmp->next;
- $count ++;
- if ($count === $pos) {
- return $tmp;
- }
- }
- } else {
- $tmp = $this->tail;
- $pos = $this->len - $pos + 1;
- $count = 1;
- while ( $tmp->pre !== null ) {
- if ($count === $pos) {
- return $tmp;
- }
- $tmp = $tmp->pre;
- $count ++;
- }
- }
- return null;
- }
- /**
- * @desc: Return the head node of the linked list
- */
- public function getHead() {
- return $this->head->next;
- }
- /**
- * @desc: Return the tail node of the linked list
- */
- public function getTail() {
- return $this->tail;
- }
- /**
- * @ desc: Query the number of nodes in the linked list
- */
- public function getLength() {
- return $this->len;
- }
- private static function _getNode($key, $data) {
- $newNode = new Node_Element ( $key, $data );
- if ($newNode === null) {
- echo "new node fail!";
- }
- return $newNode;
- }
- private function delNode($node) {
- unset ( $node );
- $this->len --;
- }
- }
- // $myList = new DoubleLinkedList ();
- // $myList->insert ( 1, "test1" );
- // $myList->insert ( 2, "test2" );
- // $myList->insert ( "2b", "test2-b" );
- // $myList->insert ( 2, "test2-c" );
- // $myList->insert ( 3, "test3" );
- // $myList->insertPosition ( 5, "t", "testt" );
- // $myList->readAll ();
- // echo "+++";
- // $myList->deletePosition(0);
- // $myList->readAll ();
- // echo "..." . $myList->getLength ();
- // var_dump ( $myList->findPosition ( 3 )->data );
- ?>
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