TLDR; Lots of practice, at least one problem every day from CTCI. The reason this article is interesting is entirely because author is actually CS student and

TLDR; Lots of practice, at least one problem every day from CTCI. The reason this article is interesting is entirely because author is actually CS student and that too from Stanford. Most CS majors anywhere in the world have to take algorithms classes and even more advanced compiler design, distributed computing, parallel programming, graph theory etc (for example, Stanford has CS161). Its hard to imagine CS student who hadn't had Introduction to Algorithms as textbook and did not had to do at least few assignments from that book. So given all that, I'm wondering how author got through those classes because those classes are usually much more demanding than tech interviews and questions are more harder (try yourself doing CS161 final exam [1]). While CTCI does have lot of material that is not covered in typical CS classes, I would think pretty much all fundamentals such as permutations and basics like checking correctness of recursive algorithms or runtime complexity etc is very well covered. In fact I would argue that anyone heavily relying on CTCI as only source would be much weaker on these fundamentals and a competent interviewer would be easily able to identify them. [1] http://web.stanford.edu/class/cs161/final-autumn16.pdf http://web.stanford.edu/class/cs161/final-autumn16.pdf