My personal experience with the ICFP programming competition suggests that you can do quite well with a fairly limited amount of time dedicated to it. My 2-man

My personal experience with the ICFP programming competition suggests that you can do quite well with a fairly limited amount of time dedicated to it. My 2-man team managed to get 2nd place in the lightning round and 8th in the main round last year, despite using my side project programming language with its half-baked implementation. We generally do not do much preparation outside of having participated in the contest for a number of years. I did a bit of library work and my partner did a bit of a refresher on the language since he doesn't use it outside of the contest, but that was about it. Prior years were similar. Granted, ICFP is a fair bit different than something like Google Code Jam. There are far fewer entries (typically around 200 or so for the main round), the task is larger, you have more time (3 days for the main round compared to 2.5 hours for a round of Code Jam) and you can compete as a team rather than an individual. I haven't really tried Code Jam yet so I can't say how much of that makes a difference.