PHP implementation of two-way queue class instance, PHP queue Instance _php tutorial

PHP implementation of two-way queue class instance, PHP queue instance

This paper introduces the bidirectional queue class and its usage of PHP implementation, which has a good reference value for the study of PHP data structure and algorithm. Share to everyone for your reference. The specific analysis is as follows:

(deque, full name double-ended queue) is a data structure that has the nature of queues and stacks. Elements in a two-way queue can be ejected from both ends, and their qualified insert and delete operations are performed at both ends of the table.

In practice, you can also have output-constrained bidirectional queues (that is, one endpoint allows insertions and deletions, the other endpoint allows only two bidirectional queues to be inserted) and a restricted bidirectional queue (that is, one endpoint allows insertions and deletions, and the other endpoint allows only two-way queues to be deleted). If an element that qualifies a bidirectional queue to be inserted from an endpoint can only be removed from that endpoint, the bidirectional queue is transformed into a stack of two stacks that are adjacent to the bottom of the stack.

The DEQue.class.php class file is as follows:

<?php/** php bidirectional queue. Support limit queue Length, input restricted, output is limited, and the output must be the same as the input settings * date:2014-04-30 * author:fdipzone * ver:1.0 * Func: * Public frontadd front-end     into row * Public frontremove front-end dequeue * Public Rearadd backend into row * pulbic Rearremove Backend dequeue * Public clear empty to column * public isfull Determines whether the column is full * Private getlength gets the column length * Private setaddnum entry column, the output dependent input when called * Private setremovenum record dequeue, output dependent input when called * p Rivate checkremove Check if output dependent input */class deque{//class start Private $_queue = Array ();//To column private $_maxlength =  0;    For the maximum column length, 0 means no limit to private $_type = 0;  To column type private $_frontnum = 0;   Number of front-end inserts private $_rearnum = 0; Number of back-end inserts/** Initialize * @param $type to column type * 1: Both ends can be input and output * 2: Front-end can only be input, back-end Input Output * 3: Front-end can only be lost Out, back-end can be input and output * 4: Back-end can only input, front-end can be input and output * 5: Back-end can only output, front-end can be input and output * 6: Both ends can be input and output, on which side input only from the end of the output * @param $max Length to Column max. */Public Function __construct ($type =1, $maxlength =0) {$this->_type = In_array ($type, Array ( , 4,5,6))?     $type: 1;   $this->_maxlength = intval ($maxlength); }/** front into row * @param Mixed $data Data * @return Boolean */Public function Frontadd ($data =null) {if ($this-&     gt;_type==3) {//Front-end input limit return false;        } if (Isset ($data) &&! $this->isfull ()) {Array_unshift ($this->_queue, $data);        $this->setaddnum (1);     return true;   } return false; }/** Front-end dequeue * @return Array */Public Function Frontremove () {if ($this->_type==2) {//front-end output limit return     Null     } if (! $this->checkremove (1)) {//check whether the input return null is dependent;      } $data = null;        if ($this->getlength () >0) {$data = Array_shift ($this->_queue);     $this->setremovenum (1);   } return $data; }/** backend into row * @param Mixed $data Data * @return Boolean */Public function Rearadd ($data =null) {if ($this-&gt     ; _type==5) {//Backend input limit return false; } if (Isset ($data) &&! $this->isfull ()) {Array_push ($this->_queue, $data);        $this->setaddnum (2);     return true;   } return false; }/** back-end dequeue * @return Array */Public Function Rearremove () {if ($this->_type==4) {//back-end output limit return n     Ull     } if (! $this->checkremove (2)) {//check whether the input return null is dependent;      } $data = null;        if ($this->getlength () >0) {$data = Array_pop ($this->_queue);     $this->setremovenum (2);   } return $data;     /** Empty the column * @return Boolean */Public Function Clear () {$this->_queue = array ();     $this->_frontnum = 0;     $this->_rearnum = 0;   return true;     }/** Determines whether the column is full * @return Boolean/Public Function Isfull () {$bIsFull = false;     if ($this->_maxlength!=0 && $this->_maxlength== $this->getlength ()) {$bIsFull = true;   } return $bIsFull; /** gets the current pair of column lengths * @return int */Private Function GetLength () {return count ($this->_queue); The/** input column, which is called when the output depends on the inputs * @param int $endpoint endpoint 1:front 2:rear */Private Function Setaddnum ($endpoint) {if ($t       his->_type==6) {if ($endpoint ==1) {$this->_frontnum + +;       }else{$this->_rearnum + +; }}}/** records a dequeue, the output depends on input when called * @param int $endpoint endpoint 1:front 2:rear */Private Function Setremovenum ($endpoin       T) {if ($this->_type==6) {if ($endpoint ==1) {$this->_frontnum--;       }else{$this->_rearnum--;     }}}/** check if output dependent input * @param int $endpoint endpoint 1:front 2:rear */Private Function Checkremove ($endpoint) {       if ($this->_type==6) {if ($endpoint ==1) {return $this->_frontnum>0;       }else{return $this->_rearnum>0;   }} return true;  }}//class end?>

The

demo.php sample code is as follows:

<?php require "DEQue.class.php"; Example 1 $obj = new DEQue (); Both front and rear end can be entered, infinite length $obj->frontadd (' a '); Front into row $obj->rearadd (' B '); Back end into row $obj->frontadd (' C '); Front into row $obj->rearadd (' d ');  The back end into row//into row array should be cabd $result = array (); $result [] = $obj->rearremove (); Back-end dequeue $result [] = $obj->rearremove (); Back-end dequeue $result [] = $obj->frontremove (); Front-end dequeue $result [] = $obj->frontremove (); Front-end dequeue Print_r ($result); The dequeue order should be DBCA//Example 2 $obj = new DEQue (3, 5); The front end can only output, the back-end input and output, the maximum length of 5 $insert = array (); $insert [] = $obj->rearadd (' a '); $insert [] = $obj->rearadd (' B '); $insert [] = $obj->frontadd (' C '); Because the front end can only output, this returns false $insert [] = $obj->rearadd (' d '); $insert [] = $obj->rearadd (' e '); $insert [] = $obj->rearadd (' f '); $insert [] = $obj->rearadd (' G ');  Over length, return false Var_dump ($insert); Example 3 $obj = new DEQue (6); Output dependent input $obj->frontadd (' a '); $obj->frontadd (' B '); $obj->frontadd (' C ');  $obj->rearadd (' d '); $result = Array (); $result[] = $obj->rearremove (); $result [] = $obj->rearremove (); Because the output relies on input, this returns null $result [] = $obj->frontremove (); $result [] = $obj->frontremove ();  $result [] = $obj->frontremove ();  Var_dump ($result);  ?>

Full instance code click here to download this site.

It is hoped that this article will be helpful to the study of PHP program algorithm design.

Implementing a two-way queue with PHP

The problem is unclear

Would like to write a queue class with PHP and a stack of classes, the class contains two methods, put the values and put the values out

Class queue{
Private $q = Array ();
Public function push ($v) {
Array_push ($this-Q, $v);

}
Public Function Shift () {
Return Shift ($this-Q);

}

}

The simplest queue.
However, using PHP to achieve data structure, do not feel a little bit to eat it?

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