RosettaCodeData/Task/Average-loop-length/Perl/average-loop-length.pl

22 lines
621 B
Raku

use List::Util qw(sum reduce);
sub find_loop {
my($n) = @_;
my($r,@seen);
while () { $seen[$r] = $seen[($r = int(1+rand $n))] ? return sum @seen : 1 }
}
print " N empiric theoric (error)\n";
print "=== ========= ============ =========\n";
my $MAX = 20;
my $TRIALS = 1000;
for my $n (1 .. $MAX) {
my $empiric = ( sum map { find_loop($n) } 1..$TRIALS ) / $TRIALS;
my $theoric = sum map { (reduce { $a*$b } $_**2, ($n-$_+1)..$n ) / $n ** ($_+1) } 1..$n;
printf "%3d %9.4f %12.4f (%5.2f%%)\n",
$n, $empiric, $theoric, 100 * ($empiric - $theoric) / $theoric;
}