rubyco https://blog.hatena.ne.jp/rubyco/ rubyco（るびこ）の日記 https://rubyco.hatenadiary.org/ am Rubyで「エラトステネスの篩」を実装しました。単純な版♪ def sieve(m) prime = (0..m).to_a (2..m).each do |p| next if not prime[p] yield(p) if block_given? (p+p..m).step(p) do |k| prime[k] = false end end prime[2..m].find_all {|p| p} end sieve(50) { |p| print "#{p}, " }; puts #=> 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41,… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Frubyco.hatenadiary.org%2Fentry%2F20060307%2Fsieve" title="エラトステネスの篩 - rubyco（るびこ）の日記" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2006-03-07 00:00:00 rich https://rubyco.hatenadiary.org/entry/20060307/sieve 1.0 100%