双向队列
<?php
class Deque{
private $queue=array();
public function addFirst($item){
return array_unshift($this->queue,$item);
}
public function addLast($item){
return array_push($this->queue,$item);
}
public function removeFirst(){
return array_shift($this->queue);
}
public function removeLast(){
return array_pop($this->queue);
}
}
?>
