Proper divisors: Difference between revisions
→{{header|Perl 6}}: Optimize, add some verbiage about optimization and concurrency
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Thundergnat (talk | contribs) (→{{header|Perl 6}}: Optimize, add some verbiage about optimization and concurrency) |
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=={{header|Perl 6}}==
{{Works with|rakudo|2018.10}}
Once your threshold is over 1000, the maximum proper divisors will always include 2 and 5 as divisors, so only bother to check multiples of 2 and 5.
There really isn't any point in using concurrency for a limit of 20_000. The setup and bookkeeping drowns out any benefit. Really doesn't start to pay off until the limit is 50_000 and higher. Try swapping in the commented out race map iterator line below for comparison.
<lang perl6>sub propdiv (\x) {
my @l = 1 if x > 1;
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my @candidates;
loop (my int $c =
#(10, *+10 ... 200_000).race.map: -> $c {
@candidates[+propdiv($c)].push: $c▼
my \mx = +propdiv($c);
next if mx < @candidates - 1;
}
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