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@ -103,11 +103,15 @@ class PreCalculatedPrimeTable : public PrimeTable { |
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::std::fill(is_prime_, is_prime_ + is_prime_size_, true); |
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is_prime_[0] = is_prime_[1] = false; |
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for (int i = 2; i <= max; i++) { |
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// Checks every candidate for prime number (we know that 2 is the only even
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// prime).
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for (int i = 2; i*i <= max; i += i%2+1) { |
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if (!is_prime_[i]) continue; |
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// Marks all multiples of i (except i itself) as non-prime.
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for (int j = 2*i; j <= max; j += i) { |
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// We are starting here from i-th multiplier, because all smaller
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// complex numbers were already marked.
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for (int j = i*i; j <= max; j += i) { |
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is_prime_[j] = false; |
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} |
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} |
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