Yeah, what did not surprise me was the fact that people jumped on to find "patterns" in the string etc. The question simply asked "Take string X and transform it into string Y". I have learned, as a life lesson, that second-guessing people is not always profitable, in fact it's not most of the times. Just give 'em what they want, with minimum complications. My post was intended for contrast.

On a lighter side, I guess one could come up with an even more braindead solution (I'd investigate substr, index, for-a-la-C etc.)