use strict;
use warnings;

use Memoize;

$| = 1;
memoize('f_fenLisesi');
my $LARGE_N = shift || 300_000;

for (\&f_fenLisesi, \&f_mjd, \&f_swampyankee) {
  print "7! = ", $_->(7), "\n";
}

time_this( \&f_fenLisesi,   'fenLisesi'  );
time_this( \&f_mjd,         'mjd'        );
time_this( \&f_swampyankee, 'swampyankee');

exit( 0 );

#--------------------------------------------------+
sub time_this {
    my ($cref, $test_name) = @_;
    my $start = time();
    print "testing $test_name: ";
    for (1 .. $LARGE_N) {
        $cref->( $_ );
    }
    printf "%d second(s)\n", time() - $start;
}

#--------------------------------------------------+
sub f_swampyankee {
    my ($n) = @_;
    my $sum = 0;
    for my $i (1 .. $n) {
        $sum += $i;
    }
    $sum;
}

##--------------------------------------------------+
sub f_fenLisesi {
    my ($n) = @_;
    return 1 if $n == 1;
    $n + f_fenLisesi( $n - 1 );
}

##--------------------------------------------------+
my @fact;
BEGIN {@fact = (0)}
sub f_mjd {
  my ($n) = @_;
  while ($#fact < $n) {
    push @fact, @fact + $fact[-1];
  }
  return $fact[$n];
}
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