隊(duì)列是一種線性表，按照先進(jìn)先出的原則進(jìn)行
單向隊(duì)列：只能從頭進(jìn)逞频，從尾出
雙向隊(duì)列：頭尾都可以進(jìn)出
<?php
class deque
{
public $queue = array();
public $length = 0;
public function frontAdd($node){
array_unshift($this->queue,$node);
$this->countqueue();
}
public function frontRemove(){
$node = array_shift($this->queue);
$this->countqueue();
return $node;
}
public function rearAdd($node){
array_push($this->queue,$node);
$this->countqueue();
}
public function rearRemove(){
$node = array_pop($this->queue);
$this->countqueue();
return $node;
}
public function countqueue(){
$this->length = count($this->queue);
}
}
?>