my @arr = map { $_->[0] }
 sort { $a->[1] cmp $b->[1] }
 map  { [ $_, sort_key($_) ] } @arr;

sub sort_key {
 my $str = shift;
 my $first = substr($str, 0, 1) eq "X" ? "0" : "1";
 return $first . $str;
}