Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
tye,
I expanded the code I came up with for combinations of a fixed size:
#!/usr/bin/perl use strict; use warnings; my $iter = combo( 30..50 ); while ( my @combo = $iter->() ) { print "@combo\n"; } sub combo { my @list = @_; return sub { () } if ! @_; my (@position, @stop, $end_pos, $done); my ($by, $next) = (0, 1); return sub { return () if $done; if ( $next ) { $by++; return () if $by > @list; @position = (0 .. $by - 2, $by - 2); @stop = @list - $by .. $#list; $end_pos = $#position; $next = undef; } my $cur = $end_pos; { if ( ++$position[ $cur ] > $stop[ $cur ] ) { $position[ --$cur ]++; redo if $position[ $cur ] > $stop[ $cur ]; my $new_pos = $position[ $cur ]; @position[ $cur .. $end_pos ] = $new_pos .. $new_pos + + $by; } } if ( $position[0] == $stop[0] ) { $position[0] == @list ? $done = 1 : $next = 1; } return @list[ @position ]; } }
I haven't analyzed its O factor or spent a lot of time with good benchmarks, but it does appear to be considerably faster for combinations of 30..50.

Cheers - L~R


In reply to Re^2: Finding all Combinations by Limbic~Region
in thread Finding all Combinations by narse

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



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

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

How do I use this?Last hourOther CB clients
Other Users?
Others exploiting the Monastery: (5)
As of 2024-03-28 19:40 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found