After iteration, the queue will be empty. Therefore, `count()` will return 0. You can circumvent this by iterating over a clone, instead of the actual queue.
https://stackoverflow.com/questions/27464012/splpriorityqueuenext-is-removing-the-item
(PHP 5 >= 5.3.0, PHP 7)
SplPriorityQueue::count — Counts the number of elements in the queue.
이 함수는 인수가 없습니다.
Returns the number of elements in the queue.
After iteration, the queue will be empty. Therefore, `count()` will return 0. You can circumvent this by iterating over a clone, instead of the actual queue.
https://stackoverflow.com/questions/27464012/splpriorityqueuenext-is-removing-the-item