If you want to be "tricky", you can pack a binary heap into a one-dimensional list:
my $heap = ['Root', 'Child1', 'Child2', 'Grandchild1', Grandchild2'];
See heapsort for a stereotypical use of binary heaps. They're not as general as n-ary trees (being strictly binary and left-balanced), but they might make an interesting example.
For further fun and games with low-level-hacking data structures, pack a binheap into a string, with either null-separated or fixed-width fields:
# "\0" is a null, right?
my $ns_heap = "R\0C1\0C2\0GC1\0GC2\0";
my $fw_heap = "R\0\0C1\0C2\0GC1GC2";
Again, this is almost gratuitously ugly, but might make a "fun" example.
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Found a typo in this node? /msg me
% man 3 strfry