47 lines
802 B
Perl
47 lines
802 B
Perl
use strict;
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use warnings;
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sub get_primes7($) {
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my ($n) = @_;
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if ($n < 2) { return (); }
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if ($n == 2) { return (2); }
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# do only odd numbers starting at 3
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my @s = ();
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for (my $i = 3; $i < $n + 1; $i += 2) {
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push(@s, $i);
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}
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# n**0.5 simpler than math.sqr(n)
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my $mroot = $n ** 0.5;
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my $half = scalar @s;
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my $i = 0;
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my $m = 3;
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while ($m <= $mroot) {
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if ($s[$i]) {
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my $j = int(($m*$m - 3) / 2);
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$s[$j] = 0;
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while ($j < $half) {
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$s[$j] = 0;
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$j += $m;
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}
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}
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$i = $i + 1;
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$m = 2*$i + 3;
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}
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my @res = (2);
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foreach (@s) {
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push(@res, $_) if ($_);
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}
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return @res;
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}
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my $startTime = time();
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my $periodTime = $ENV{'RUN_TIME'};
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my @res;
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while ((time() - $startTime) < $periodTime) {
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@res = get_primes7(10000000);
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print "Found ".(scalar @res)." prime numbers.\n";
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}
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