Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl: the Markov chain saw
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
interesting approach that reminded me about some old project that needed some permutations generations stuff... so, i've checked up that code and here i come with a reviewed standalone version:
#!/usr/bin/perl -w # DESCRIPTION: Generate permutations in lexicographic order # USAGE: ./permlex.pl <term1> <term2> <term3> ..... use strict; die "bleah... nothing to permutate\n" if $#ARGV<0; my @terms = @ARGV; my $n = $#ARGV; my @a = (0..$n); genperm(); exit(0); sub genperm { print join(" ",@terms[@a]),"\n"; my ($k,$j) = ($n-1,$n); $k-- while ($k>=0 and $a[$k]>$a[$k+1]); return(0) if ($k<0); $j-- while ($a[$k]>$a[$j]); swap($j,$k++); $j=$n; swap($j--,$k++) while ($j>$k); genperm(); } sub swap { my ($i,$j) = @_; my $t = $a[$i]; ($a[$i],$a[$j]) = ($a[$j],$t); }

as you may see, it's a pure lexicographic permutations generator algorithm, as in the books ;-)

oh, not to forget, just checked up on cpan and found out there is a Algorithm::Permute module. here is a lame example for module users ;-)

#!/usr/bin/perl -w use strict; die "bleah... nothing to permutate\n" unless defined @ARGV; use Algorithm::Permute qw(permute permute_ref); print join(" ", @$_), "\n" for permute(\@ARGV);

--
AltBlue.


In reply to RE: Permutations and combinations by AltBlue
in thread Permutations and combinations by merlyn

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!
  • 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
  • Outside of code tags, you may need to use entities for some characters:
            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 perusing the Monastery: (4)
    As of 2014-09-20 09:13 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      How do you remember the number of days in each month?











      Results (157 votes), past polls