I wrote an article on a Google interview question in June, 2006 describing the problem and offering a simple solution. What makes this article interesting is that several people came up with better ideas and very thought provoking comments. If you are a puzzle enthusiast, you will surely enjoy the article; if not for the article but more importantly for the alternative solutions proposed. They excel in many cases the original solution; they also provide lots of original thoughts. If I like anything as much as simple thoughts, it is original thoughts.