I agree with this post. I've turned down Google interviews twice precisely because I was immersed in personal projects and didn't want to spend the time needed to practice algorithm writing just for a test. I could understand if they ask you practical questions like "when and why would you use a trie?" that seems more appropriate than "write a trie on my whiteboard or you're not smart enough to work here." None of their engineers are writing trees by hand and in fact are actively encouraged not to "reinvent the wheel."