#!/usr/bin/perl
my @unsorted = qw(a,b,c c,b,a a,a,a,a b,b); 

my @sorted = map { $_->[1] } 
            sort { $b->[0] <=> $a->[0] } 
             map { [ tr/,// , $_ ] } @unsorted; 
print "@sorted\n"

##</code><code>##

$ perl -le '@unsorted = qw(a,b,c c,b,a a,a,a,a b,b); @sorted = map { $_->[1] } sort { $b->[0] <=> $a->[0] } map { [tr/,// , $_] } @unsorted; print "@sorted"'
a,a,a,a a,b,c c,b,a b,b