From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Lennart Borgman <lennart.borgman@gmail.com>
Cc: Leo <sdl.web@gmail.com>, Drew Adams <drew.adams@oracle.com>,
emacs-devel@gnu.org
Subject: Re: `completion-in-region'
Date: Sun, 11 Apr 2010 22:10:50 -0400 [thread overview]
Message-ID: <jwv39z1xw25.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <q2ve01d8a51004111406z173c8423j4a5ae03eee524a3b@mail.gmail.com> (Lennart Borgman's message of "Sun, 11 Apr 2010 23:06:44 +0200")
>> If you use ".*?a.*?b.*?c", then yes it gives the
>> same matches but it also has the same O(N^3) worst case.
> This is not the right place perhaps to educate me on this, but to me
> it looks like just three linear searches with the summed length for
> the searches equal to that of the candidate strings. Is not that O(N)?
When matched against "ababab", it will do the following:
- search for a in the string.
- for each match of a, search for b in the remaining string.
- for each match of b, search for c in the remaining string.
These are 3 nested loops, each of them doing a number of iterations
proportional to N, so you get O(N^3) complexity.
Stefan
next prev parent reply other threads:[~2010-04-12 2:10 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-06 14:37 `completion-in-region' Leo
2010-04-09 3:05 ` `completion-in-region' Stefan Monnier
2010-04-11 12:56 ` `completion-in-region' Leo
2010-04-11 15:32 ` `completion-in-region' Stefan Monnier
2010-04-11 18:05 ` `completion-in-region' Drew Adams
2010-04-11 19:44 ` `completion-in-region' Stefan Monnier
2010-04-11 19:56 ` `completion-in-region' Drew Adams
2010-04-11 20:49 ` `completion-in-region' Stefan Monnier
2010-04-11 21:13 ` `completion-in-region' Drew Adams
2010-04-11 20:08 ` `completion-in-region' Lennart Borgman
2010-04-11 20:51 ` `completion-in-region' Stefan Monnier
2010-04-11 21:06 ` `completion-in-region' Lennart Borgman
2010-04-12 2:10 ` Stefan Monnier [this message]
2010-04-12 9:46 ` `completion-in-region' Lennart Borgman
2010-04-12 13:10 ` `completion-in-region' Stefan Monnier
2010-04-12 14:50 ` `completion-in-region' Davis Herring
2010-04-11 21:12 ` `completion-in-region' Drew Adams
2010-04-12 15:36 ` `completion-in-region' Leo
2010-04-12 18:10 ` `completion-in-region' Stefan Monnier
2010-04-12 15:51 ` `completion-in-region' Leo
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