#!/usr/bin/perl

my $template   = shift || die "usage: $0 <template>\n";
my @pattern    = split( //, $template );
my $levels     = scalar( @pattern );

my $vowels     = [ qw( a e i o u y ) ];
my $consonants = [ qw( b c d f g h j k l m n p q r s t v w x z ) ];

output_cv( 0, \@pattern, $consonants, $vowels, "" );

sub output_cv {
  my( $level, $pattern, $consonants, $vowels, $string ) = @_;

  # if we have no more levels in the pattern, output the buffered string
  if( $level == scalar( @$pattern ) ) {
    print "$string\n";
  } else {
    # figure out which array at this pattern level
    my $array = $pattern->[$level] eq 'C' ? $consonants : $vowels; 

    foreach my $ele ( @$array ) {
      # start new buffer string
      my $new_string = $string . $ele;
      # recurse to next level
      my $new_level = $level + 1;
      output_cv( $new_level, $pattern, $consonants, $vowels, $new_string );
    }
  }
}