doubletrouble.rb

#!/usr/bin/ruby

def winloss
  if rand(2) == 1
    return true
  else
    return false
  end
end

def session
  bankroll = 10
  
  bet = 0.1
  while bankroll > 0 && bankroll < 15
    if winloss
      bankroll += bet * 2
      bet = 0.1
    else
      bankroll -= bet
      bet = bet * 2 # double up
    end
    #puts "bankroll is #{bankroll}, bet is #{bet}"
  end
  
  if bankroll >= 15
    return true
  else
    return false
  end
end

win = 0
lose = 0

10000.times do
  results = session
  if results
    win += 1
  else
    lose += 1
  end
end

puts "#{win} wins, #{lose} losses"