use Data::Dumper;
my @array = ( 0, 1, 2, 3, 4, 5 );

my %uniq;
@uniq{@array[1..$#array]} = ();

print Dumper \%uniq;


##</code><code>##

$VAR1 = {
          '4' => undef,
          '1' => undef,
          '3' => undef,
          '2' => undef,
          '5' => undef
        };

##</code><code>##

use Data::Dumper;
my %uniq;
my @aoa = ( ['foo',0],  # Changed from 'AoA' to 'aoa'. Thanks to bobf.
            ['foo',1],
            ['foo',2],
            ['foo',3],
            ['foo',4], 
            ['foo',5],);

@uniq{ @aoa[ 1 ... $#aoa ]->[-1] } = ();
print Dumper \%uniq;


##</code><code>##

$VAR1 = {
          '5' => undef
        };