montyhall.rb

require 'bigdecimal'

switch = true
wins = 0

1000.times do |k|
  doors = [false, false, false]
  doors[rand 3] = true

  selection = rand 3

  host_door = nil
  while !host_door || doors[host_door] == true || host_door == selection do
    host_door = rand 3
  end

  print "Round #{k} #{doors.inspect}: You selected #{selection}. Host opened #{host_door}. "

  selection = ([0, 1, 2] - [host_door, selection])[0] if switch == true

  if doors[selection] == true
    wins += 1
    puts "You Win!"
  else
    puts "You Lose!"
  end
end

puts "Total Percent: #{wins / 1000.00}"