my @new_list = map { $_->[0] }
               sort { $b->[1] cmp $a->[1] }
               map  { ( my $s = $_ ) =~ s/\[(\d+)/sprintf('%010d%s', length($1),$1)/eg; [ $_, $s ] }
	                      @split_list;


print "@new_list\n";

##</code><code>##

a2_2[10] a2_2[2] a2_2[1] a2_1[10] a2_1[2] a2_1[1] a2_10[10] a2_10[2] a2_10[1] a1_2[10] a1_2[2] a1_2[1] a1_1[10] a1_1[2] a1_1[1] a1_10[10] a1_10[2] a1_10[1] a10_2[10] a10_2[2] a10_2[1] a10_1[10] a10_1[2] a10_1[1] a10_10[10] a10_10[2] a10_10[1]