#!/usr/bin/perl
use warnings;
use strict;
use feature qw(say);

my @strings = qw(xxxxxx.2012-50.yyyyy
                 xxxxxx.2012-51.yyyyy
                 xxxxxx.2012-52.yyyyy
                 xxxxxx.2013-1.yyyyy
                 xxxxxx.2013-2.yyyyy
                 xxxxxx.2013-3.yyyyy
                 xxxxxx.2013-4.yyyyy
                 xxxxxx.2013-10.yyyyy
                 xxxxxx.2013-11.yyyyy
                );

my %cache;
my @sorted = sort {
    ($cache{$a} //= generate_key($a))
        cmp
    ($cache{$b} //= generate_key($b))
} @strings;

say for @sorted;

sub generate_key {
    my $s = (split /\./, shift)[1];
    my ($year, $number) = split /-/, $s;
    return $year . sprintf '-%03d', $number;
}