bash$ cat unreadable
my $d=scalar(@b)/3 # @b is the array with the content of the file
for (my$i=0; $i<=$#ddts; $i++){
#@ddts is the array in which is the result of an html form
for (my $index=0;$index<=($d-1);$index++)
{my $x=(($#b-1)-$index*3);# i calculate the position of the second word from each row, there is the html type i need
$new="<td><input type=\"$b[$x]\" name=\"$b[$x-1]\"></td>";
print "<table><tr><td>$ddts[$i]</td>$new</tr></table>";
}
}

bash$ perltidy unreadable

bash$ cat unreadable.tdy
my $d = scalar(@b) / 3    # @b is the array with the content of the file
  for ( my $i = 0 ; $i <= $#ddts ; $i++ ) {

    #@ddts is the array in which is the result of an html form
    for ( my $index = 0 ; $index <= ( $d - 1 ) ; $index++ ) {
        my $x =
          ( ( $#b - 1 ) - $index * 3 )
          ; # i calculate the position of the second word from each row, there is the html type i need
        $new = "<td><input type=\"$b[$x]\" name=\"$b[$x-1]\"></td>";
        print "<table><tr><td>$ddts[$i]</td>$new</tr></table>";
    }
}

bash$