From: Andreas Ericsson Date: Wed, 10 Apr 2013 15:23:21 GMT Subject: Re: [rfh] do I need to use something more complex to do this? Message-ID: <516583E9.9030200@op5.se> In-Reply-To: <7vk3oao3e5.fsf@alter.siamese.dyndns.org> On 04/10/2013 04:40 PM, Junio C Hamano wrote: > I have set of items with two attributes, , and would like to > keep them in some data structure in such a way that it is efficient > to (1) add a new item to the data structure, and (2) pick an item in > a specific order. There can be multiple items that share the same > value for X, or Y, or both X and Y, and it does not matter in what > order items comes out among those that share the same . > > The type of X is totally ordered. The type of Y also usually is, but > Y can take a special value U(nspecified). > > Now on to the "specific" order I want to pick an item. I'd like to > take the item with the largest value of Y in general, and tiebreaking > on the value of X which also I prefer to take from larger to smaller. > > But with a twist. > > When I am picking an item , there should be no item > remaining in the data store with a value of Y that is smaller than m > (duplicates are allowed, so there can still be items with Y=m), and > also when I am picking , there should be no item with > Y=Unspecified that has a value of X that is equal or smaller than n. > So X is primary sort and Y is secondary, except Y=Undefined trumps all other values for Y, but never trumps X as primary sort. Can't you just have U be the largest unsigned integer value of the type you choose? For this particular application, I doubt there's any risk of the defined numbers catching up with it. I might have missed something though. This seems a bit too trivial for you to ask for help. -- Andreas Ericsson andreas.ericsson@op5.se OP5 AB www.op5.se Tel: +46 8-230225 Fax: +46 8-230231 Considering the successes of the wars on alcohol, poverty, drugs and terror, I think we should give some serious thought to declaring war on peace.