Why not combine the two approaches? The first solution which comes to my mind calls for a single iteration through the elements of @list with a lookup hash, %hash, that is used to avoid duplicate processing.

For example ...

my %hash;
while (my $item = shift @list) {
    next if exists $hash{$item}++;

    .
    .

}

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In reply to Re: best data structure by rob_au
in thread best data structure by Anonymous Monk

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