If you pull out your handy dandy perldoc and type 'perldoc -q duplicate', which searches for the word 'duplicate' in the FAQ section of the perldoc, you come upon this handy entry:

ded430-deb-175-30:/home/buu/torrent# perldoc -q duplicat
Found in /usr/share/perl/5.8/pod/perlfaq4.pod
       How can I remove duplicate elements from a list or array?

       There are several possible ways, depending on whether the array
+ is ordered and whether you wish to preserve
       the ordering.

       a)  If @in is sorted, and you want @out to be sorted: (this ass
+umes all true values in the array)

               $prev = "not equal to $in[0]";
               @out = grep($_ ne $prev && ($prev = $_, 1), @in);

           This is nice in that it doesn't use much extra memory, simu
+lating uniq(1)'s behavior of removing only
           adjacent duplicates.  The ", 1" guarantees that the express
+ion is true (so that grep picks it up) even if
           the $_ is 0, "", or undef.

       b)  If you don't know whether @in is sorted:

               undef %saw;
               @out = grep(!$saw{$_}++, @in);

       c)  Like (b), but @in contains only small integers:

               @out = grep(!$saw[$_]++, @in);

       d)  A way to do (b) without any loops or greps:

               undef %saw;
               @saw{@in} = ();
               @out = sort keys %saw;  # remove sort if undesired

       e)  Like (d), but @in contains only small positive integers:

               undef @ary;
               @ary[@in] = @in;
               @out = grep {defined} @ary;

       But perhaps you should have been using a hash all along, eh?
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