Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!selfless.tophat.at!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.039 X-Spam-Evidence: '*H*': 0.92; '*S*': 0.00; 'instance,': 0.05; 'pm,': 0.10; 'am,': 0.14; 'received:209.85.214.174': 0.14; 'received :mail-iw0-f174.google.com': 0.14; 'wrote:': 0.14; 'angelico': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'itself;': 0.16; 'rebert': 0.16; 'header:In-Reply-To:1': 0.21; 'thu,': 0.22; 'found,': 0.23; '\xa0if': 0.23; 'code': 0.24; "i'm": 0.27; 'work.': 0.28; 'message-id:@mail.gmail.com': 0.28; 'received:209.85.214': 0.28; '24,': 0.29; "won't": 0.30; 'print': 0.31; 'to:addr:python-list': 0.33; 'rather': 0.34; 'chris': 0.34; 'quite': 0.36; 'received:google.com': 0.37; 'received:209.85': 0.37; 'fair': 0.37; 'url:org': 0.38; 'but': 0.38; 'subject:: ': 0.38; 'received:209': 0.39; 'to:addr:python.org': 0.39; 'hope': 0.60; 'stop': 0.62; 'perfect': 0.64; 'square': 0.67; 'prime': 0.73; 'subject:this': 0.76; 'subject:..': 0.82; 'num': 0.84; 'factors': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:content-transfer-encoding; bh=dXDPj2hFYiXUjuxESe7R42LMuXx+XOr1HtM0MNw6Z1U=; b=xIaVPAAzJbTbSIOrmvOp6Wi3j+luyyJYzqfP5XSknh9pUU+yviuH3rNLTgj3BI8BXM 91lJdFz7L0ELRtIZfEBTD8gAT8n17DmfMzd0/KeNRgC6T0UuYcL2QYVYpQw09noYTUOr aTBCQdeFBhhPiIbmMygVbNyNf6FtOWgA2ZLbc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=NMbGZqLI20TxqH1jjKAGMJk/e3cn9bNhls7xpUSsao6PUNxuuijxttLXny6p5IeuWS 8lsfgd8qpG46+vMc9VMcb8H3oNXsfWCWeMIxzewCNT0a2WNAtKJvpsKkSeSvmTGZ9RPW +helgMUkNiC1sk1sFH8rT4RdFFVigQqN7beug= MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 9 Jun 2011 19:25:06 +1000 Subject: Re: Any Better logic for this problem.. From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 29 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1307611509 news.xs4all.nl 49178 [::ffff:82.94.164.166]:39595 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:7283 On Thu, Jun 9, 2011 at 7:06 PM, Chris Rebert wrote: > On Thu, Jun 9, 2011 at 1:31 AM, Ganapathy Subramanium > wrote: >> Hi Guru's, >> I'm working on a solution to find the prime factor of the number >> This part of the code works..=A0http://www.pastie.org/2041584 > > For the archives, that code is: > > for items in prime_numbers: > =A0 =A0if num % items =3D=3D 0: > =A0 =A0 =A0 =A0prime_factors.append(items) > > print 'The prime factors are : ' , prime_factors Prime factors don't quite work that way. The prime factors of 24, for instance, are 2, 2, 2, and 3. But if you're looking for _unique_ prime factors, then this will work. Rather than find all prime numbers up to num, stop at sqrt(num) - it's not possible to have any prime factors larger than that. (Be sure to include the square root itself; range(2,sqrt(num)) won't work if num is a perfect square. Use range(2,sqrt(num)+1) for safety.) That will save a fair amount of effort. Also, if you divide num by each factor found, it'll make the numbers smaller, which may be faster. Hope that helps! Chris Angelico