#!/usr/bin/perl -w

use strict;
use Data::Dumper;

# The HoA below may come in varying
# sizes: from "key1" to "key 50"

my $hash = {
    'key1' => [ 1,   2,   3, 4 ],
    'key2' => [ 10,  20,  30 ],
    'key3' => [ 100, 200, 300 ],
    'key4' => [ 'a','b','c','dood']
};

my (@b, @base);

#compute combos
for(sort keys %{$hash}){
	concat_arrays(\@b, $hash->{$_});
}

#filter computations
@base = grep{ 
		my $count = () =  $_ =~ m/\-/g;
		($count == (scalar(keys %{$hash})-1)); 
	}sort @base;

#double check
print $_."\n" for(@base);

sub concat_arrays
{
	my ($baseref, $newref) = @_;
	foreach my $new (@{$newref}){
		if(scalar(@{$baseref})){
			foreach my $base (@{$baseref}){
				push @base, $base." - ".$new;
			}
		}else{
			push @base, $new;
		}
	}
	@b = @base;
}