Strong and weak primes: Difference between revisions
Added Perl example
Thundergnat (talk | contribs) m (→{{header|Perl 6}}: add some commas) |
SqrtNegInf (talk | contribs) (Added Perl example) |
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real 0m3.011s</pre>
=={{header|Perl}}==
{{trans|Perl 6}}
{{libheader|ntheory}}
<lang perl>use ntheory qw(primes);
sub comma {
(my $s = reverse shift) =~ s/(.{3})/$1,/g;
$s =~ s/,(-?)$/$1/;
$s = reverse $s;
}
sub below { my($m,@a) = @_; $c = 0; while () { return $c if $a[++$c] > $m } }
my @primes = @{ primes(10_000_019) };
for $p (1 .. $#primes - 1) {
$x = ($primes[$p - 1] + $primes[$p + 1]) / 2;
if ($x > $primes[$p]) { push @weak, $primes[$p] }
elsif ($x < $primes[$p]) { push @strong, $primes[$p] }
else { push @balanced, $primes[$p] }
}
for ([\@strong, 'strong', 36, 1e6, 1e7],
[\@weak, 'weak', 37, 1e6, 1e7],
[\@balanced, 'balanced', 28, 1e6, 1e7]) {
my($pr, $type, $d, $c1, $c2) = @$_;
print "\nFirst $d $type primes:\n", join ' ', map { comma $_ } @$pr[0..$d-1], "\n";
print "Count of $type primes <= @{[comma $c1]}: " . comma below(1e6,@$pr) . "\n";
print "Count of $type primes <= @{[comma $c2]}: " . comma scalar @$pr . "\n";
}</lang>
{{out}}
<pre>First 36 strong primes:
11 17 29 37 41 59 67 71 79 97 101 107 127 137 149 163 179 191 197 223 227 239 251 269 277 281 307 311 331 347 367 379 397 419 431 439
Count of strong primes <= 1,000,000: 37,723
Count of strong primes <= 10,000,000: 320,991
First 37 weak primes:
3 7 13 19 23 31 43 47 61 73 83 89 103 109 113 131 139 151 167 181 193 199 229 233 241 271 283 293 313 317 337 349 353 359 383 389 401
Count of weak primes <= 1,000,000: 37,780
Count of weak primes <= 10,000,000: 321,750
First 28 balanced primes:
5 53 157 173 211 257 263 373 563 593 607 653 733 947 977 1,103 1,123 1,187 1,223 1,367 1,511 1,747 1,753 1,907 2,287 2,417 2,677 2,903</pre>
=={{header|Perl 6}}==
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