Beefy Boxes and Bandwidth Generously Provided by pair Networks
No such thing as a small change

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
I'd try your routine here,but I can't work out where I supply the start and end?

Globals! See the post before. (there is no point in passing them as long as you don't use any divide and conquer approach)

or just:

use strict; use warnings; use Data::Dumper; $|=1; my $start="B"; my $stop="E"; my %graph =( 'F' => ['B','C','E'], 'A' => ['B','C'], 'D' => ['B'], 'C' => ['A','E','F'], 'E' => ['C','F'], 'B' => ['A','E','F'] ); $start="A"; $stop="Z"; %graph =( A => ["N", "W", "J", "L", "C", "E", "X", "T", "O", "H"], C => ["Z", "J", "Q", "U", "S", "T", "N", "P", "D", "O"], E => ["P", "G", "U", "F", "X", "A", "Y", "K"], H => ["W", "O", "J"], J => ["Z", "U", "B", "Q", "N", "I", "V", "F", "C", "P"], K => ["X", "H", "J", "C", "P", "W", "E", "S", "Q"], L => ["C", "B", "V", "A", "S", "J", "O", "H"], N => ["R", "G", "K", "N", "Q", "W", "C", "U", "E", "V"], O => ["K", "G", "X", "A", "Z", "W"], P => ["O", "G", "F", "T", "E", "U", "L", "H", "B", "R"], Q => ["V", "N", "X", "U", "D", "M", "S", "C", "R", "G"], R => ["D", "S", "K", "X", "O", "U"], S => ["Q", "E", "T", "P", "G", "Z"], U => ["Y", "V", "U", "X", "R", "W", "M", "G", "K", "N", "A"], W => ["P", "E", "G", "Y"], X => ["Z", "H", "R", "L", "J", "W", "A", "E", "X", "T", "D"], Y => ["J", "X", "G"], Z => ["K", "A", "Z"], ); my $anzahl=0; my $time0=time; track($start); { my %seen; sub track { my @path=@_; my $last=$path[-1]; $seen{$last}=1; for my $next (@{$graph{$last}}) { next if $seen{$next}; if ($next eq $stop) { #print join ("->",@path,$stop),"\n"; $anzahl++; print "$anzahl at ",time-$time0,"\n" if $anzahl%10000==0; } else { track(@path,$next); } } delete $seen{$last}; } } print $anzahl;

Of course @path could be global too and the recursion could be liniarized...

Not talking about nifty short circuit algorithms...

Cheers Rolf

In reply to Re^10: Finding All Paths From a Graph From a Given Source and End Node by LanX
in thread Finding All Paths From a Graph From a Given Source and End Node by neversaint

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?

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

    How do I use this? | Other CB clients
    Other Users?
    Others scrutinizing the Monastery: (3)
    As of 2021-04-19 03:55 GMT
    Find Nodes?
      Voting Booth?

      No recent polls found