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Super-d numbers: Difference between revisions

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Super-d numbers (view source)

Revision as of 16:36, 24 November 2019

1,916 bytes removed ,  4 years ago
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Cut convoluted concurrent code
(promoted draft task to a (full) task.)
m (Cut convoluted concurrent code)
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=={{header|Perl 6}}==
{{works with|Rakudo|2019.07.1}}
===Simple===
2 - 6 take a few seconds, 7 about 17 seconds, 8 about 90... 9, bleh... around 700 seconds.
 
Line 329 ⟶ 328:
17546133 32613656 93568867 107225764 109255734 113315082 121251742 175461330 180917907 182557181
704.7 sec.</pre>
 
===Concurrent===
Since waiting can be tiresome, make things faster with the <code>race</code> concurrency function. The only problem is that we're not sure what the stopping point is ahead of time, so when it seems safe to quit (calculate a few more result than strictly needed, since the parallel workers don't coordinate), break out of the concurrent block by raising an exception. The usual concurrency caveats apply: <code>@super</code> must be sized ahead of time, and only modified with an atomic operation (⚛++).
 
Concurrency makes little difference for d < 6, but the benefits accrue rapidly after that (greater than 10-fold speed-up for d = 8, with an 8-core CPU). However, in the end, you'll still have to wait a quite bit or the super-9 values.
<lang perl6>sub super-d ($d,$max) {
my $max-plus = $max + floor 2*$max/$d;
my @super[2*$max-plus];
{
my $digits = $d x $d;
my $chunk = 250 * $d;
my atomicint $found = 0;
(0, 1*$chunk, 2*$chunk ... *).race(:1batch).map: -> $i {
@super[$found⚛++] = $_ if ($_ ** $d * $d).contains($digits) for 1+$i .. 1+$i+$chunk;
X::AdHoc.new.throw if $found ≥ $max-plus;
}
CATCH { when X::AdHoc { return @super.grep(so *).sort.head($max) } }
}
}
 
say "$_: " ~ join ' ', super-d($_,10) for 2..9;</lang>
{{out}}
<pre>2: 19 31 69 81 105 106 107 119 127 131
3: 261 462 471 481 558 753 1036 1046 1471 1645
4: 1168 4972 7423 7752 8431 10267 11317 11487 11549 11680
5: 4602 5517 7539 12955 14555 20137 20379 26629 32767 35689
6: 27257 272570 302693 323576 364509 502785 513675 537771 676657 678146
7: 140997 490996 1184321 1259609 1409970 1783166 1886654 1977538 2457756 2714763
8: 185423 641519 1551728 1854230 6415190 12043464 12147605 15517280 16561735 18542300
9: 17546133 32613656 93568867 107225764 109255734 113315082 121251742 175461330 180917907 182557181</pre>
 
=={{header|Phix}}==
SqrtNegInf
2,392

edits

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