I don't know about efficiency, but something like this comes to mind:

     my( %hash, @order );  # assume these are initialized

     # 1 - map
     my @numbers = map{ exists $hash{ $_ } ? $hash{ $_ } : 999 } @orde
+r;

     # 2 - foreach
     my @numbers;
     foreach my $name ( @order ) {
             push @numbers, ( exists $hash{ $name } ? $hash{ $name } :
+ 999 );
      }
[download]

Something like that. Does that work?