#!/usr/bin/perl 
 
use strict; 
use warnings; 
 
 
my @files = qw( 
    Windows_Server_A_20120901 
    Windows_Server_A_20120902 
    Windows_Server_A_20120903 
    Windows_Server_B_20120901 
    Windows_Server_B_20120902 
    Windows_Server_B_20120903 
    Windows_Server_XZ_20120903 
    Windows_Server_XZ_20120901 
    Windows_Server_XZ_20120902 
    Windows_Server_XZ_20120903 
); 
 
my %newest; 
 
foreach my $file ( @files ) { 
    no warnings qw(uninitialized); 
    my ($name, $date) = $file =~ /^(.+)_(\d+)/; 
    $newest{$name} = $date if $date > $newest{$name}; 
} 
 
while (my ($name, $date) = each %newest) { 
    print "${name}_$date\n"; 
}