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Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question

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在 2012年1月28日星期六UTC+8上午7时30分25秒，pete写道：
> Tim Rentsch wrote:
> > 
> > pete 
>  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

Looking for an integer number rasied to a power of 6  that fits all

conditions in the range should be easy even without writing a program.

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Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question pete <pfiland@mindspring.com> - 2012-01-07 22:03 -0500
  Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-26 10:11 -0800
    Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question pete <pfiland@mindspring.com> - 2012-01-27 17:06 -0500
    Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question pete <pfiland@mindspring.com> - 2012-01-27 18:30 -0500
      Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-31 06:19 -0800
        Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question Willem <willem@toad.stack.nl> - 2012-03-08 22:26 +0000
      Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 22:28 -0800
        Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question pete <pfiland@mindspring.com> - 2012-02-01 18:47 -0500
          Re: [Hardest Maths Statement Puzzle] Toughest Math Statement Question Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 12:24 -0800

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