# ($k,$v) = rhe_1(%hash);

sub rhe_1 (\%) {
  my $key = (keys %{ $_[0] })[rand keys %{ $_[0] }];
  return ($key, delete $_[0]{$key});
}

##</code><code>##

# @keys = keys %hash;  # done ONCE
# ($k,$v) = rhe_2(%hash,@keys);

sub rhe_2 (\%\@) {
  my $key;
  do {
    $key = rand @keys
  } until exists $_[0]{$_[1][$key]};
  return ($_[0]{$_[1][$key]}, delete $_[0]{$_[1][$key]});
}

##</code><code>##

# %seen = ();  # done ONCE
# @array = ([k,v], [k,v], ...);
# ($k,$v) = rhe_3(@array,%seen);

sub rhe_3 (\@\%) {
  my $idx;
  do { $idx = rand @{ $_[0] } } while $_[1]{int $idx}++;
  return @{ $_[0][$idx] };
}