Proper divisors: Difference between revisions
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m (Undo revision 272833 by Gerard Schildberger (talk) edited wrong page.) |
Thundergnat (talk | contribs) (→{{header|Perl 6}}: Optimize, add some verbiage about optimization and concurrency) |
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=={{header|Perl 6}}== |
=={{header|Perl 6}}== |
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{{Works with|rakudo|2018.10}} |
{{Works with|rakudo|2018.10}} |
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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. |
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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. |
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<lang perl6>sub propdiv (\x) { |
<lang perl6>sub propdiv (\x) { |
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my @l = 1 if x > 1; |
my @l = 1 if x > 1; |
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my @candidates; |
my @candidates; |
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loop (my int $c = |
loop (my int $c = 10; $c <= 20_000; $c += 10) { |
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#(10, *+10 ... 200_000).race.map: -> $c { |
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my \mx = +propdiv($c); |
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next if mx < @candidates - 1; |
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} |
} |
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