sub hash {
    my ($ref, $hash) = @_;
    for my $el (@$ref) {
        $hash = $hash->{$el} ||= {};
    }
}

my $h = {};
my @array = qw/ a b c d e /;
hash( \@array, $h);
print Dumper( $h );

$VAR1 = {
      'a' => {
           'b' => {
                'c' => {
                     'd' => {
                          'e' => {}
                        }
                   }
              }
         }
    };