Article View: comp.lang.pascal.misc
Article #12Re: Tough FACTORIAL math problem...
From: Tim Martin
Date: Sun, 25 Feb 1996 06:08
Date: Sun, 25 Feb 1996 06:08
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1820 bytes
Bruce Kaskel wrote: > > So after you have finished the n-th iteration, you have multiplied your > number by n, removed the trailing zeros, and subtracted 10000 until the > number is not greater than 10000. Are you claiming that you end up with > a number with the same last digit as n! ? > > Strictly speaking this is not correct. > > Take the 3125-th iteration. Your algorithm yields 995. > But the rightmost non-zero digit of 3125! is not 5. > > --Bruce Kaskel Duh...uh..well, sorry to shoot you down but: The original USACO problem (where this idea came from...and whoever posted it to this group needs a serious course in ethics) specified that you only needed to test up to 1000!....So, his idea works within the program specs BTW-I didn't enter the competition, but I also solved it that particular way...with a little more clumsy approach using strings instead of longints, but the basic concept is the same - you only need to save the last 4 non-zero digits, because you are only ever multiplying the result by something less than 1000. Tim tass@armory.com
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Path: arc1-ca.pugleaf.net!usenet.cis.ufl.edu!caen!usenet From: Tim Martin <tass@armory.com> Newsgroups: comp.lang.pascal.misc,comp.lang.c++,comp.lang.c,comp.lang.pascal.borland Subject: Re: Tough FACTORIAL math problem... Date: Sun, 25 Feb 1996 01:08:15 -0500 Organization: University of Michigan Engineering, Ann Arbor Message-ID: <312FFCCF.33209502@armory.com> References: <4fr8be$ass@news.iconn.net> <4g2n5u$kqj@sun001.spd.dsccc.com> <danpop.824595562@rscernix> <4gaucn$cdu@beyond.escape.com> <4gh4cq$8eo@agate.berkeley.edu> NNTP-Posting-Host: tass@pm085-07.dialip.mich.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.0 (X11; I; Linux 1.2.3 i486)