google Imagine you want to search through Google to find a particular page. You want to do it in a second. And you're going to just do it the brute force way, assuming you could even reach all of those pages in that time.

假设你想通过,搜索一个特定的网页,你想在1秒内得到结果,然后你就只管去做了,认为能在1秒内遍历遍所有的网页。

麻省理工公开课 - 计算机科学及编程导论课程节选