CPP/solution_2: add mask implementation #985
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davepl
commented
Nov 6, 2024
PrimeCPP/solution_2/PrimeCPP_PAR.cpp
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| @@ -61,7 +61,55 @@ class BitArray { | |||
| array[index(n)] |= (uint8_t(1) << (n % 8)); | |||
| } | |||
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| constexpr size_t size() const | |||
| static constexpr uint32_t buildSkipMask(size_t skip, size_t offset) | |||
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Is there a backwards-Kernigan way to do this? Seems like someone has probably thought about how to create a mask before, and there's likely a better way. Like maybe as bits are moved to the mask, you clear them from i and stop when i is zero?
rbergen
changed the title
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This splits solution_2 into two distinct solutions:
solution_2, which now uses bit masking and direct array access
solutiion_2a, which uses half as much memory, no direct array access, and is faster
Why keep solution_2 at all? Because one day I hope to learn SIMD and will need direct array access, so want to keep the basic methodology around
drag-raceas the target branch.