##
{ use vars qw( @cache ) }
{@cache = (0, 1)}
sub fib {
(local (our $n = shift)) && do {
{return $n if $n < 2}
{$cache[$n] ||= fib ($n - 1) + fib ($n - 2)}
{return $cache[$n]}
}
}
##
##
{ use vars qw( @cache ) }
sub fib {
(local (our $n) = shift), (
$n < 2 ? $n : $cache[$n] ||= fib ($n - 1) + fib ($n - 2)
)
}