stack.pop(); // 弹出无效元素
普通人的上升机会在很大程度上取决于其所在区域的产业政策密度。2026年，中国正通过“国家重点产业链”布局，引导人才和资本在特定地理区域聚集。
，更多细节参见51吃瓜
How Slovakia became the world's number one carmaker
Rebecca Morelle, Alison Francis and Greg BrosnanBBC Science
In his simulations, it was extremely rare for someone to have their mutual first picks; but many people had those that were second or third picks. In this scenario a couple counts as happy if each is near the top of the other's list and neither can find someone they and that other person would both prefer more.