ランダム選ばれた二人がコインを渡し合うとどうなるか

pass_coin_randomly.rb

INITIAL_COINS = 0
NUMBER_OF_MEMBER = 100
NUMBER_OF_TRIAL = 10_000_000

members = Array.new(NUMBER_OF_MEMBER) { |i| INITIAL_COINS }

NUMBER_OF_TRIAL.times do |n|
  if n % 100_000 == 0
    puts n.to_s + "\t" + members.map(&:to_s).join("\t")
  end

  from = rand(NUMBER_OF_MEMBER)
  to   = rand(NUMBER_OF_MEMBER)

  move_coins = 1
  # 徐々にインフレするケース（桃鉄？）
  # move_coins = (10**(n*1.0/NUMBER_OF_TRIAL)).floor

  members[from] -= move_coins
  members[to]   += move_coins
end

puts NUMBER_OF_TRIAL.to_s + "\t" + members.map(&:to_s).join("\t")