uchihime-gacha.rb

#!/usr/bin/env ruby

class String
  def for_2ch
    self.gsub(/ {2,}/) do |spaces|
      len = spaces.length
      if len.even?
        "　" * (len / 2)
      else
        ("　" * (len / 2)) + " "
      end
    end
  end
end

# config me
sr_per = 3.00r
hr_per = 17.80r
set_price = 5800r
set_stars = 6600r

yen_per_star = set_price / set_stars
header = <<-EOT
10000人がガチャ引いたときの回数毎のSR・HRハズレ人数
  SR確率#{sr_per.to_f.round(2)}%、HR確率#{hr_per.to_f.round(2)}%、星くず1個#{yen_per_star.to_f.round(2)}円（#{set_price.to_i}円/#{set_stars.to_i}個）で計算

*    連（回数    金額）: SR率（ハズレ） HR率（ハズレ）

EOT
puts header.for_2ch

sr_win_probability = sr_per / 100
sr_lose_probability = 1 - sr_win_probability
hr_win_probability = hr_per / 100
hr_lose_probability = 1 - hr_win_probability
(1..30).each do |i|
  times = i * 11
  sr_win = (1 - (sr_lose_probability ** times))
  sr_lose = 1 - sr_win
  hr_win = (1 - (hr_lose_probability ** times))
  hr_lose = 1 - hr_win
  cost = 4000 * yen_per_star * i
  str = "* %3d連（x%2d %6d円）: %3d%%（%4d人） %3d%%（%4d人）" % [
    times,
    i,
    cost.to_f.round,
    (sr_win * 100).to_f.round,
    (sr_lose * 10000).to_f.round,
    (hr_win * 100).to_f.round,
    (hr_lose * 10000).to_f.round,
  ]
  puts str.for_2ch
end