I would create a HoH in addition to the HoA and replace that double nested foreach loop:

next if exists $edgeHoH{$a}{$b};

$edgeHoH{$a}{$b} = undef;

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Then you can get rid of the whole 'if $good' if/else statement, and just push unconditionally (and there was no difference in your 'if' and 'else' actions anyway).

Update: Oops, misread another question. But now it seems like you just need a simple hash to store the b's, and skip if you've already seen it.

In reply to Re: H of A optimization by runrig
in thread H of A optimization by abitkin

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