my @min_keys = sort { length($a) <=> length($b) || $a cmp $b } keys %$
+hashref;
my $min = length $min_keys[0];

for ( 1 .. $#min_keys ) {
    if ( length $min_keys[$_] != $min ) {
        splice @min_keys, $_;
        last;
    }
}
# maxstr & random
print join "\t", $min_keys[-1], $min_keys[ rand @min_keys ];
[download]

my @list = qw(zero one two three four five six seven eight nine ten el
+even twelve);

my ($maxstr, $random) = find_shortest( @list );
print join "\t", $maxstr, $random;

sub find_shortest {
    my ($pos, $len, $maxstr, @min) = (0, undef, '', 0, undef);
    my %dispatch = (
        -1 => sub {
                  ($len, $pos) = (length($_), 0);
                  ($min[$pos], $maxstr) = ($_, $_);
              },
         0 => sub {
                  $min[++$pos] = $_;
                  $maxstr = $_ if $_ gt $maxstr;
              },
         1 => sub { return },
    );
    for ( @_ ) {
       if ( ! defined $len ) {
           $len = length();
           ($min[$pos], $maxstr) = ($_, $_);
           next;
       }
       $dispatch{ length($_) <=> $len }->();
    }
    return ($maxstr, (@min[0..$pos])[rand $pos]);
}
[download]