Problem 14 (written in Ruby)

こちらも計算量がかなり多い様子。
2.18GHz Core Duoで2分ほど。

def create_pattern(n)

  ret = []

  while n != 1 do

    ret << n

    if n & 0x01 == 1 then

      n = 3*n+1

    else

      n = n / 2

    end

  end

  ret << 1

  return ret

end
longest_n = 0

longest = 0

(1...999999).each do |n|

  pattern = create_pattern(n)

  if longest < pattern.size then

    longest_n = n

    longest = pattern.size

  end

end

Problem:
http://odz.sakura.ne.jp/projecteuler/index.php?Problem%2014