c:\@Work\Perl\monks>perl -wMstrict -le
"use List::Util qw(maxstr);
 ;;
 my @dates = qw(
   12112014
   12012014
   01052015
   12202014
   12022014
   02202015
   03102015
   01012011
   09092015
   04092015
   );
 ;;
 my $most_recent =
   unpack 'x4a*',
   maxstr
   map pack('a4a*', unpack('x4a4', $_), $_),
   @dates
   ;
 ;;
 print $most_recent;
"
09092015