Most of the answers given involve a hash, which is a good idea; the reason for this is that arrays are good for storing, but not for looking up information - hashes are much better suitable for that. You might want to redesign your program slightly, so you store your information in a hash to start with.

However, since you will be sorting the array, there might be a different approach: first sort it, and since it is sorted, remove duplicate elements, which, because of the sorting, will be sequential.

use strict;
use warnings;

my @array = (1,2,5,6,4,2,1,2,3,4,6,4,3,2,4,6,6);

my @sorted = sort {$a <=> $b} @array; # numerically

@array = (sort shift @sorted); # overwrite old array

while (my $element = shift @sorted) {
   # if the element differs from the last added, keep it
   # otherwise discard
   if ($element != $array[-1]) { 
      push (@array, $element);
   }
}
# array is now sorted, no duplicate elements
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