Re: Generating the ith permutation of N elements
| Newsgroups | gmane.games.devel.algorithms |
|---|---|
| Message-ID | <99976243.274959.1275417271881.JavaMail.open-xchange@oxltgw00.schlund.de> |
One mapping is to convert your index i to base-e for e elements. That's surjective/onto. But IIR discrete maths there's more than one definition of ith permutation On 01 June 2010 at 18:57 Yannick Letourneau <[email protected]> wrote: > I'm looking for a way to generate the ith permutation of N elements, at > approximately O(N) cost. > > All algorithms I've seen need the (i-1)th permutation in order to derive the > ith permutation from it (e.g. they work incrementally). > > I would just like to give it a number in the range > > 0 <= i < N! > > and it would spit out the ith permutation, without requiring to compute the > ones that come before it (which would be O(N!) ). > > Is that possible ? > > Any pointers appreciated. > > Yannick ------------------------------------------------------------------------------ _______________________________________________ GDAlgorithms-list mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithms-list