NP完全性的概念为理解计算问题的复杂性提供了一个强大的工具。

I don’t like to be told what to do.

A wise man said: before you speak， let your words pass through three gates. At the first gate， ask yourself， "Is it true？" At the second gate， ask "Is it necessary？" At the third gate， ask， "Is it kind？"

我了解到我的痛苦可以成为我的力量。