use strict;
use warnings;
use Digest::MD5 qw(md5_hex);

my @li  = ('a'..'z','a');

shuffle(\@li) for 1..5;
print "@li\n";

sub shuffle{
    my $ref = shift;
    my @idx = 0 .. scalar @$ref -1;
    @$ref = 
        map{ $ref->[$_->[0]] }
        sort{ $a->[1] cmp $b->[1] }
        map{ [ $_, md5_hex($_.$$.time) ] }@idx;
}