gistfile1.txt

sub getHammingNumbers(int $howMany, boolean $all --> List[BigInteger]) {
    my $three = BigInteger.Parse("3");
    my $five = BigInteger.Parse("5");
    my $completedNumbers = List[BigInteger].new;
    my $frontierSet = SortedSet[BigInteger].new;
    $completedNumbers.Add(BigInteger.One);
    $frontierSet.Add(BigInteger.op_LeftShift(BigInteger.One, 1));
    $frontierSet.Add(BigInteger.One * $three);
    $frontierSet.Add(BigInteger.One * $five);
    loop (my $count = 1; $count < $howMany; $count++) {
        my $lowestNumber = $frontierSet.Min;
        $frontierSet.Remove($lowestNumber);
        if ($all) {
            $completedNumbers.Add($lowestNumber)
        } else {
            $completedNumbers[0] = $lowestNumber
        }
        $frontierSet.Add(BigInteger.op_LeftShift($lowestNumber, 1));
        $frontierSet.Add($lowestNumber* $three);
        $frontierSet.Add($lowestNumber* $five)
    }
    $completedNumbers
}

my $stopwatch = Diagnostics::Stopwatch.StartNew;

say "First 20 Hamming numbers: ";
my $twenty = getHammingNumbers(20, true);
loop (my $i=0;$i<$twenty.Count;++$i) { say $twenty[$i] }
say "1691st Hamming number: " ~ getHammingNumbers(1691, false)[0];
say "One millionth Hamming number: " + getHammingNumbers(1000000, false)[0];
say "Elapsed: " ~ $stopwatch.Elapsed