I know that it can be done with a hash of arrays (which I also was having trouble with), but I want to do it with a hash of hashes, if possible

Why on earth would you want to do that? For each letter sequence you want the list of numbers that were associated with it. That shouts for a hash of arrays.

In the loop, when you have $lets and $nums, collect the numbers belonging to $lets: 

push @{ $plates{ $lets} }, $nums;

[download]
To print the results: 
print "$_ ", join( ', ', @{ $plates{ $_}), "\n" for sort keys %plates;

[download]
(Code untested)

Anno

In reply to Re: hash of hashes by Anno
in thread hash of hashes by volcan

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