Re: How do I remove the duplicates from the array?

[hdb]

Here is an answer as cryptic (and somewhat wasteful) as your requirements (ignoring LanX extras):

use warnings;
use strict;

my @array  = qw(-20 20 1 1 2 2 2 9 3 -4 -4 5 -20 20 7 7 7);
my @array1 = qw( 10 11 7 9 3 3 3 1 3  4  5 5   1 30 8 7 8);

for( map{ my $k=$_; [ sort{ $array1[$b]<=>$array1[$a] } grep{ $k eq $a
+rray[$_] } 0..$#array ] } @array ) {
        shift @$_ if @$_==1 or $array1[$$_[0]] ne $array1[$$_[1]];
        $array[$_] = $array1[$_] = '' for @$_;
}
$"=','; print "\@output  = (@array);\n\@output1 = (@array1);\n";

[LanX]

maybe less cryptic?

  DB<154> @a0 =  (-20,20,1,1,2,2,2,9,3,-4,-4,5,-20,20);
 => (-20, 20, 1, 1, 2, 2, 2, 9, 3, -4, -4, 5, -20, 20)

  DB<155> @a1 = ( 10,11,7,9,3,3,3,1,3, 4, 5,5,  1,30); 
 => (10, 11, 7, 9, 3, 3, 3, 1, 3, 4, 5, 5, 1, 30)

  DB<156> map { push @{$group{$a0[$_]}},$a1[$_] } 0..$#a0

  DB<157> sub highlander { 
             my @sort = sort @{ shift() } ; 
             return $sort[-1]>$sort[0] ? $sort[-1] : undef 
          } 

  DB<158> @high{keys %group } = map { highlander($_) } values %group 
=> (undef, 5, undef, undef, 30, 9, 10, undef)

  DB<159> map { ($a0[$_],$a1[$_])=() if $a1[$_] != $high{ $a0[$_] } } 
+0..$#a0 

  DB<160> \@a0
 => [
  -20,
  undef,
  undef,
  1,
  undef,
  undef,
  undef,
  undef,
  undef,
  undef,
  -4,
  undef,
  undef,
  20,
]

  DB<161> \@a1
 => [
  10,
  undef,
  undef,
  9,
  undef,
  undef,
  undef,
  undef,
  undef,
  undef,
  5,
  undef,
  undef,
  30,
]

[hdb]

I do not understand the line $sort[-1]>$sort[0] ? $sort[-1] : undef. What if the values are 7, 8, 8? How will it discard the whole thing? I know the OPs spec is rather cryptic but my understanding was, that the values are to be blanked out if the max occurs more than once.

[LanX]

> I know the OPs spec is rather cryptic but my understanding was, that the values are to be blanked out if the max occurs more than once.

hmm ... ok my understanding was to discard if all are maximum, see (3,3,3)

But your definition is indeed closer to the naming highlander, maybe peak was better.

edit

For highlander compare with [-2] if there are more than 2 elements.

BTW: "cryptic" is an euphemism for incompetent ... if you can't express such a problem in words you don't deserve being called a programmer.