#!/usr/bin/env perl

use strict;
use warnings;
use feature qw (say);

my @dates = qw{
  12112014
  01052015
  02202015
  03102015
  01012011
  04092015
  09092015
};

my %hash;

for (@dates) {
    my ( $m, $d, $y ) = unpack q(a2a2a4);
    $hash{qq($y$m$d)} = $_;
}

for ( sort { $a <=> $b } keys(%hash) ) {
    say $hash{$_};
}
__END__

karls-mac-mini:monks karl$ ./dirs.pl 
01012011
12112014
01052015
02202015
03102015
04092015
09092015