A Formula for the Number of Days in Each Month
I believe Zeller's Congruence had already solved this, no?<p>Zeller's is based upon calculating the day of the week, but it also calculates days in the month and accounts for leap years. Plus, it's been around since the 19th century and is used in many major programming languages to calculate date (its implementation is sometimes a first year Comp Sci course project for introductory programming): <a href="http://en.wikipedia.org/wiki/Zeller%27s_congruence" rel="nofollow">http://en.wikipedia.org/wiki/Zeller%27s_congruence</a><p>For a programming example that does this same thing: <a href="https://github.com/mwhawkins/JavaZellers" rel="nofollow">https://github.com/mwhawkins/JavaZellers</a><p>How did this make the front page of HN being a problem which has already been solved and well documented for almost 200 years? Not to knock the author, as they put in some time apparently, but was just curious.