http://www.perlmonks.org?node_id=294826


in reply to Worst thing you ever made with Perl

Took a while to dig up ... i think i wrote this in early 1997: 
#!/usr/local/bin/perl

#################################################
# hanoi.pl
# translated from C++ to Perl by Jeff Anderson
# original C++ code by Brenda Parker
#################################################

#recursive function
sub Hanoi {
    local($number, $from, $to, $aux);
    ($number, $from, $to, $aux) = @_;

    if ($number == 1) {
        print "Move 1 from $from to $to<BR>";
    }
    elsif ($number != 0) {
        &Hanoi($number-1,$from,$aux,$to);
        print "Move $number from $from to $to<BR>";
        &Hanoi($number-1,$aux,$to,$from);
    }
}
        
#this library contains the function &GetFormInput which reads
#and parses the form data
require('libs/forms-lib.pl');


#read input from the form
%input = &GetFormInput();

print "Content-type: text/html\n\n";

$number = $input{'pegs'};

unless ($number =~ /^[0-1]?[0-9]$/) {
    print "Numeric, not alpha-numeric!<BR>";
    exit;
}
    

print <<"EOM";
<HTML>
<HEAD>
<TITLE>Towers Result</TITLE>
</HEAD>
<BODY>
EOM

if ($number < 1) {
    print "You are really cruel, zero pegs. Go away.<BR>";
} elsif ($number > 15) {
    print "I said 15 is the max, go tie up your own processor!<BR>";
} else    {
    print "For $number pegs:<P>";
    &Hanoi($number,'A','B','C');
}

print <<"EOM";
</BODY>
</HTML>
EOM

[download]

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

Replies are listed 'Best First'.
2Re: Worst thing you ever made with Perl
by jeffa (Bishop) on Sep 28, 2003 at 23:29 UTC
    And now, the re-write: 
    use strict;
use warnings;
use CGI qw(header param);
use HTML::Template;

my @solution;
my $tmpl = HTML::Template->new(filehandle => \*DATA);

if (param('go')) {
   my $discs = param('discs');
   $discs = 1 if $discs < 1 or $discs > 15;
   
   hanoi($discs,'A','B','C');
   
   $tmpl->param(
      solution => \@solution,
      discs    => $discs,
   );
}

print header, $tmpl->output;

# original algorithm learned from Brenda Parker
sub hanoi {
   my ($number, $from, $to, $aux) = @_;

   if ($number == 1) {
      push @solution, {step => "Move 1 from $from to $to"};
   }
   elsif ($number != 0) {
      hanoi($number-1,$from,$aux,$to);
      push @solution, {step => "Move $number from $from to $to"};
      hanoi($number-1,$aux,$to,$from);
   }
}

__DATA__
<html>
<head>
<title>Towers of Hanoi</title>
</head>
<body>

<form>
<p>
Enter number of discs desired (15 is MAX):
<input type="text" name="discs" size="2" />
</p>
<input type="submit" name="go" value="Solve" />
</form>

<tmpl_if solution>
<hr/>
Solving for <tmpl_var discs> discs:
<ol>
<tmpl_loop solution>
   <li><tmpl_var step></li>
</tmpl_loop>
</ol>
</tmpl_if>

</body>
</html>

    [download]

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]
[d/l]

In Section Meditations