如果真的是interview问题，这个题目真的是tricky

1。 Given a file of URLs, how to find the top 10 most popular domains? If the file is really large (containing tens of millions of URLs), and we don't want to know the exact top 10 most popular domains, what is the quickest way to find the approximate top 10 most popular domains? domian name和url是不一样de啊。这个问题不像个简单的统计问题，首先要找出最快的从url中提取domain name的办法，然后..... 2。How to efficiently store a billion URLs? url本身就是由domain name 加上path组成的， 所以....