use strict;
use warnings;

my %hash;
assign(\%hash, 'aa', 'bb', 'cc', 'value');
print $hash{aa}{bb}{cc};

sub assign {
    my $p = shift;
    my $val = pop;
    my $last = pop;
    for (@_) {
        $p->{$_} = {} if !$p->{$_};
        $p = $p->{$_};
    }
    $p->{$last} = $val;
}