Programming puzzles: processing lists!

[pier4r]

(08-16-2017 12:51 PM)pdo Wrote:  Hello,

I don't know if this has been mentioned already for #37, and excuse me if I'm barging in and stating the obvious here, but I think there is a simple proof that the total number of match-day pairings for any even N is equal to (N-1)(N-3)(N-5)...1 and an efficient/elegant way of enumerating them would probably be recursive in nature.

Paul

Well I cannot have an opinion on this if you don't say more. How do you get the (N-1)(N-3)(N-5)...(N-N-1) formula? Would be nice to have a reference.

Plus I am pretty sure the problem is already long solved because people had to make calendars for sport leagues long ago. Personally I try first to attack the problem on my own (it is even better when other people are interested and try on their own) before checking existing results that would spoil the fun. Also I learned that when I try by myself and I make some sort of progress and then I get stuck, I appreciate and understand existing results better.