Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!news.glorb.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail
NNTP-Posting-Date: Fri, 27 Jan 2012 17:30:18 -0600
Message-ID: <4F233391.5FC@mindspring.com>
Date: Fri, 27 Jan 2012 18:30:25 -0500
From: pete <pfiland@mindspring.com>
Reply-To: pfiland@mindspring.com
Organization: PF
X-Mailer: Mozilla 3.04Gold (WinNT; I)
MIME-Version: 1.0
Newsgroups: comp.lang.c
Subject: Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question
References: <d2f643df-1028-4906-808d-faa935f94fa0@f8g2000prm.googlegroups.com> <4F090789.D54@mindspring.com> <kfnaa5a2v1l.fsf@x-alumni2.alumni.caltech.edu>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 67
X-Usenet-Provider: http://www.giganews.com
NNTP-Posting-Host: 4.154.217.124
X-Trace: sv3-J6G6wnfHYnEGLsWzWszSca8qM0tc9KF+9YNU85OPKOMuDCSOXknTvUYOWCaTZ1cWfsm1qoIO/xqiXY2!sxoKC7DEljBmAck3ylrZiCk1odWTIQRrhEfIaLDOd/VVTrJz7gXLDS7jWeqFlTDD6wIG7lvs9yNJ!AdjoWiSrAA==
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly
X-Postfilter: 1.3.40
X-Original-Bytes: 3045
Xref: x330-a1.tempe.blueboxinc.net comp.lang.c:16323

Tim Rentsch wrote:
> 
> pete <pfiland@mindspring.com> writes:
> 
> > divya bisht wrote:
> >>
> >> Toughest Math Statement Question
> >> (Source : http://hardest-puzzle.blogspot.com/2011/12/toughest-math-statement-question.html
> >> )
> >>
> >> I am thinking of a 6-digit number. The sum of the digits is 43.
> >>
> >> And only two of the following three statements about the number are
> >> true:
> >>
> >> (1) it's a square number,
> >> (2) it's a cube number, and
> >> (3) the number is under 500000.
> >
> > [snip program -- 114 lines of code, 24 lines of comments]
> 
> Seems like a rather long program for the problem...  how
> about this instead?
> 
> #include <stdio.h>
> 
> int digit_sum_of_equals( unsigned number, unsigned total );
> 
> int
> main(){
>     const unsigned SUM = 43;
>     unsigned  i = 999,  j = 99,  s, c;
>     /***  's' is the square of 'i',  'c' is the cube of 'j'  ***/
> 
>     printf( "Looking for six digit numbers whose digits total %u...\n", SUM );
> 
>     while(  s = i*i,  c = j*j*j,  s > 99999  ||  c > 99999  ){
> 
>         if(  s > c  &&  s < 500000  &&  digit_sum_of_equals( s, SUM )  ){
>             printf( "  %u == %u**2\n", s, i );
>         }
> 
>         if(  c > s  &&  c < 500000  &&  digit_sum_of_equals( c, SUM )  ){
>             printf( "  %u == %3u**3\n", c, j );
>         }
> 
>         if(  s == c  &&  s >= 500000  &&  digit_sum_of_equals( s, SUM )  ){
>             printf( "  %u == %u**2 == %u**3\n", s, i, j );
>         }
> 
>         if(  s >= c  )  i--;
>         if(  c >= s  )  j--;
>     }
> 
>     return  0;
> }
> 
> int
> digit_sum_of_equals( unsigned n, unsigned t ){
>     return  n == 0  ?  t == 0  :  digit_sum_of_equals( n/10, t - n%10 );
> }

The algorithm seems to be a little more clever.
I'll have to study it a bit.

-- 
pete