NP完全性的概念为理解问题的复杂性提供了一个强大的工具。

世事犹如书籍，一页页被翻过去。人要向前看，少翻历史旧账。

Sustainability isn't a cost—it's an investment in our future.

In the end, survival is not about how much you have, but how well you can use what you have.

我是一个喜欢在顶端的人。