Untested:

my $p= \%hash;
my $last= pop @splittedline;
foreach @splittedline {
  $p->{$_}={} if (not exists $p->{$_});
  $p= $p->{$_};
}
$p->{$last}= 1;
[download]

I'm sure someone else will find a more elegant solution ;-). (though I don't consider the obvious solution with eval elegant)