Lösung zu Blatt 6 --- OO-Datenbank Anwendungen (WS 2002)

Die Welt ist klein

#!/usr/local/bin/perl -w

use strict;
use IO::File;

my %name; my ($name, $pers, $knows, @knows, $last); my $met = {};
my $file = shift || "huck.dat";
my $fh = new IO::File $file || die "Cannot open file $file\n";
while(<$fh>) {
   chomp;
   next if /^[ *#]/;
   if (/^(\w+) (.*)/) { $name{$1} = $2; }
   if (/^(&|\d+[^:]*):(.*)/) {
      $knows = $2;
      unless ($1 =~ /^&/) { @knows = (); }
      push @knows, split(/;|,/, $knows);
      foreach $pers (@knows) {
	 foreach $knows (@knows) {
	    next if $pers eq $knows;
	    $met->{$pers}->{$knows} = 1;
	 }
      }
   }
}
$fh->close;
print "The following persons have been found: ";
print join(", ", sort keys %{$met}).".\n";
print "Please enter the person's key: ";
chomp($name = <>);
die "Unknown person $name" if !defined($name{$name});
my ($steps) = (0);
my %done = (); my (@more) = ($name); my (@newmore) = ();
while ($#more >= 0) {
   print "$name knows in $steps steps: ";
   foreach $pers (sort @more) {
      next if defined $done{$pers};
      print "$pers ";
      push @newmore, (keys %{$met->{$pers}});
      $done{$pers} = 1;
   }
   print "\n";
   @more = @newmore; @newmore = ();
   $steps++;
}