AIZU ONLINE JUDGE: Programming Challenge 0150 Twin Prime N = 10007 sieve = [*0..N] 2.upto(Math.sqrt(N).to_i) do |i| next if sieve[i].zero? 2.upto(N / i) {|j| sieve[i * j] = 0} end sieve = sieve[2..-1].reject {|x| x.zero?} until (n = $<.get…