my @array = <>;
my %hash;
@hash{@array}=();
print keys %hash;

my @sorted = sort @array;
my @clean = ();

my $before = undef;
foreach (@sorted) {
   push @clean, $_ if (not defined $before) or ($_ ne $before);
   $before = $_;
}

use warnings;
use strict;

my @array = <>;
my @uniq= map {
    $_->[0]
} grep {
    ! $_->[1]
} sort {
    my $v = $a->[0] cmp $b->[0];
    $a->[1] = 1 unless $v or $b->[1];
    $v
} map {
    [$_]
} @array;

print @uniq;

use strict;
use warnings;

my @array = <>;
my @uniq;
my %hash;
for (@array) {
  push @uniq, $hash{$_} = $_ unless exists $hash{$_};
}
print @uniq;