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my %keys = (
    a=>1,
...

# note that entry 0 is where the unmatched elements wind up...
print map{ "@{ $final[$_] }\n" } grep defined $final[$_],1..$#final;

foreach(@records)
{
    my @flds=split /\|/;
    push @{$final[$keys{$flds[3]}||0]},$_;
}