From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Newsgroups: gmane.emacs.help Subject: Re: Easy to add with push but not to the end of a list Date: Wed, 30 Nov 2022 15:10:51 +0100 Message-ID: References: <878rju96i5.fsf@dataswamp.org> <87tu2i660c.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="O/nURswXTkC4lAos" Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="542"; mail-complaints-to="usenet@ciao.gmane.io" To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Nov 30 15:11:47 2022 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1p0NoO-000ATo-AV for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 30 Nov 2022 15:11:44 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p0Nng-0004Bw-WD; Wed, 30 Nov 2022 09:11:01 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p0Nnd-0004Ar-RV for help-gnu-emacs@gnu.org; Wed, 30 Nov 2022 09:10:57 -0500 Original-Received: from mail.tuxteam.de ([5.199.139.25]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p0Nnb-0007Du-Td for help-gnu-emacs@gnu.org; Wed, 30 Nov 2022 09:10:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tuxteam.de; s=mail; h=From:In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:To:Date:Sender:Reply-To:Cc:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=T/38m2abkoyjzJIRsP2jlmySXFOaoXXgeMdrX9AVCik=; b=kLcUncgd3BeO+u0qAjsHobaC7X yRlfWfIlrXJAJSAmGFKPUkeCwo06LAcJ2ufqMeAKGPUGPHiJL/rzuLBcLqoztMFOdVdWt7JWf5hk3 U+p70h4StnOz8lScfIp8/eDYGswJe1UFYDegQ1WpuWDthufnjgZXoKikcmYMSL+CFzPdC0mWjZOJV SEPViF5oS9oRmouqsojVZGuKlcEKfooxwrkpxQGc/xDCMU6axnWo5LbpMMq+XbCzWfWpedcIoCMBl ZnORYN31VTIDLsKzacq1n8bhCXAMdjflqbEJaudrjmkkDh87kl54wZi1vun4PZILcEp0Dhn5M/u9y iKFyOO0A==; Original-Received: from tomas by mail.tuxteam.de with local (Exim 4.94.2) (envelope-from ) id 1p0NnX-0000Wp-F0 for help-gnu-emacs@gnu.org; Wed, 30 Nov 2022 15:10:51 +0100 Content-Disposition: inline In-Reply-To: <87tu2i660c.fsf@dataswamp.org> Received-SPF: pass client-ip=5.199.139.25; envelope-from=tomas@tuxteam.de; helo=mail.tuxteam.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:141269 Archived-At: --O/nURswXTkC4lAos Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 28, 2022 at 11:58:27PM +0100, Emanuel Berg wrote: > Stefan Monnier via Users list for the GNU Emacs text editor wrote: >=20 > > Add them in the reverse order and finish with a simple > > `reverse`. That's a very standard design pattern with > > singly-linked lists (and in many/most cases the final > > `reverse` can be an `nreverse`). >=20 > I thought about `nreverse' but if that changes all the CDRs > then that's linear as well i.e. O(n), otherwise you could do > nreverse, `push', and nreverse again ... The pattern is push, push, push, push... nreverse. Amortized costs, it's called. It makes O(n^2) into O(n). Cheers --=20 t --O/nURswXTkC4lAos Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRp53liolZD6iXhAoIFyCz1etHaRgUCY4dkZQAKCRAFyCz1etHa RhQTAJ4kllbGLU8EIlyjyv0+xweWiS1DxwCggkf82L9UQhqv7nJuEkgVeXeqZuQ= =xF7A -----END PGP SIGNATURE----- --O/nURswXTkC4lAos--