Solution #6 - Eliminate the Last

sub elim_last
{
    my $s = shift;
    my $non_occur = "\x{1}" . ("\0" x length($s)) . "\x{1}";
    $s =~ s/\.([^\.]*)$/$non_occur$1/;
    $s =~ tr/.//d;
    $s =~ s!$non_occur!.!;
    return $s;
}