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

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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

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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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