Generating the ith permutation of N elements
Yannick Letourneau <[email protected]> Tue, 1 Jun 2010 12:57:24 -0400
| Newsgroups | gmane.games.devel.algorithms |
|---|---|
| Message-ID | <9E4A58AAF133E74A9114B0FA0F2FCC6B8256ECBB@MDC-MAIL-CMS01.ubisoft.org> |
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