sub ton_pascal
{
    my $rows = shift;
    my $last_row = [ ];
    my $this_row = [ 1 ];
    
    last unless ($rows > 0);
    print "1\n";
    for (my $i = 1; $i < $rows; ++$i) {
        $last_row = $this_row;
        $this_row = [ 1 ];
        for (my $j = 1; $j < $i; $j++) {
            push(@$this_row, $last_row->[$j - 1] + $last_row->[$j]);
        }
        push(@$this_row, 1);
        print join(' ', @$this_row) . "\n";
    }    
}