#
# Find all the words for a given phone number.
#
# This is clean Perl programming. I doubt this program
# can be expressed in less lines.
#
# $Id: phone.pl,v 1.2 2002/06/24 20:17:24 renaud Exp $
#

@zero  = ( 0 );
@one   = ( 1 );
@two   = qw( a b c );
@three = qw( d e f );
@four  = qw( g h i );
@five  = qw( j k l );
@six   = qw( m n o );
@seven = qw( p q r s );
@eight = qw( t u v );
@nine  = qw( w x y z );

@name = qw( zero one two three four five six seven eight nine );


die "Usage: $0 number\n" unless (@ARGV);

$number = shift @ARGV;

f($number, '');


sub f
{
   my($digits, $letters) = @_;

   unless ($digits =~ s/^(.)//)		# remove first digit
   {
      print "$letters\n";
   }
   else
   {
      foreach (@{ $name[$1] })		# map digit to letters
      {
         f($digits, $letters . $_)
      }
   }
}