Beefy Boxes and Bandwidth Generously Provided by pair Networks
go ahead... be a heretic
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Here's a fairly straightforward sieve. It finds solutions by repeatedly applying the basic functions to the already-found solutions, so it finds solutions for some incredibly large numbers, but doesn't get 9 (for example), likely due to the limit I put on factorial (no inputs larger than 150). Output strings are effectively unary RPN.
use strict; use warnings; use bigint; # Each element of @formulas is an an op-string: # a string of Fs and Ss, indicating factorial # and square root, in order applied to get the # index my %formulas = (3 => '3'); my $found_new = 1; while ($found_new) { $found_new = 0; # Apply factorial to all formulas while (my ($v, $ops) = each %formulas) { if ($v < 150) { $v = fact($v); $ops .= 'F'; exists $formulas{$v} or $found_new = $formulas{$v} = $ops; } } # Apply sqrt to all formulas while (my ($v, $ops) = each %formulas) { $v = int(sqrt($v)); $ops .= 'S'; exists $formulas{$v} or $found_new = $formulas{$v} = $ops; } } for (sort { $a <=> $b } keys %formulas) { print "$_: $formulas{$_}\n"; } sub fact { my $f = 1; for (2..$_[0]) { $f *= $_ } $f; }
Update: instead of iterating a given number of times, iterates until no new solutions are found.

Caution: Contents may have been coded under pressure.

In reply to Re: Challenge: Chasing Knuth's Conjecture by Roy Johnson
in thread Challenge: Chasing Knuth's Conjecture by kvale

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others lurking in the Monastery: (4)
    As of 2019-11-11 22:28 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      Strict and warnings: which comes first?



      Results (63 votes). Check out past polls.

      Notices?