8 lines
159 B
Ruby
8 lines
159 B
Ruby
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def eratosthenes(n)
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nums = [nil, nil, *2..n]
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(2..Math.sqrt(n)).each do |i|
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(i**2..n).step(i) { |m| nums[m] = nil } if nums[i]
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end
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nums.compact
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end
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