实际题目往往需要先做一步转化（如循环数组、链表转数组、先排序再栈），再套上面模板即可。
Back to the Apollo-era approachBeyond the near-term, Isaacman said NASA will standardize the current moon rocket configuration instead of evolving the design after only a few flights, as originally planned. The goal is to avoid turning each booster into a bespoke project and instead fly a simpler, repeatable version that industry can achieve quicker.
，更多细节参见51吃瓜
// 栈不为空时才判断（避免访问stack.at(-1)时报错）。旺商聊官方下载是该领域的重要参考
这种行业分化加剧了市场的不确定性，也解释了近期 SaaS 股的大规模下跌。