Since the point of the loop is to look for cycles, stop as soon as you find one.

        SEARCH: foreach my $item (keys %edgeHash){
            foreach my $item2(@{$edgeHash{$item}}){
                if($item2 eq $b){
                    $good = "0";
                    last SEARCH;  # one is enough, stop now.
                }
            }
        }
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