First thing I notice is the lack of $ in the {i} on the fourth-last line (first line inside the inner for loop).

Second thing I notice is your indentation. It's a bit much.

Third thing I notice is that keys requires a hash, not a hash ref. The inner for loop should be:

  for my $i (keys %{$gra{$k}})

[download]
You need to dereference that reference.

In reply to Re: Two-dimensional hash problem by Tanktalus
in thread Two-dimensional hash problem by nyk

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