剑指offer(PHP版改写)---两个栈实现队列

$arr1 = array();
$arr2 = array();

function push($node){
    global $arr1;
    array_push($arr1,$node);
}

function pop(){
    global $arr1;
    global $arr2;

    if (!empty($arr2)){
       return array_pop($arr2);
    }else{
        while (!empty($arr1)){
            array_push($arr2,array_pop($arr1));
        }
        return array_pop($arr2);
    }
}

push(1);
push(2);
push(3);
print_r($arr1);
print_r(pop());

$stack = array();
function mypush($node)
{
    // write code here
    global $stack;
    return $stack[]=$node;
}
function mypop()
{
    global $stack;
    if($stack){
        return array_shift($stack);
    }
    return $stack;
}