出處 https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=3644
雲端硬碟分享題目：https://drive.google.com/file/d/1GdBt0cVcHHr7mphrUsi5FqUdBMf0Z5u2/view?usp=sharing
解題策略：優先權佇列