You are nearly there with the hash idea, but missed a simplification. Just step through your AoA in one loop and store the keys in a separate hash. If you find a duplicate, delete the Array entry (or whatever else you want to do with duplicates):

my %found;
my $i=0;
while ($i<@$AOA) {
  my $key = $A->[1] . '-' . $A->[3];
  if (exists $found{$key}) {
    splice(@$AOA,$i,1);
  }
  else {
    $found{$key}=1;
    $i++;
  }
}

[download]

(Untested code). If you need to do some processing of the deleted item, change above line to my $deleteditem=splice(@$AOA,$i,1);.

UPDATE: Thanks go to moritz for detecting that I forgot to increment $i. Corrected

In reply to Re: Optimize code | remove duplicates from AOA. by jethro
in thread Optimize code | remove duplicates from AOA. by ashish.kvarma

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