Prisoner's Dilema

# Solution to prisoner's dilema
# http://www.cartalk.com/content/prison-switcharoo-0?question
# https://news.ycombinator.com/item?id=7286279


$TOTAL_NUM_PRISONERS = 23

$switch_a = rand() > 0.5
$switch_b = rand() > 0.5

$prisoners_who_have_visited = [false] * $TOTAL_NUM_PRISONERS
$cycles = 0

def we_have_all_visited()
    if $prisoners_who_have_visited.any?{|pr| pr==false}
        puts "\nYou will all be fed to the aligators now... (after #{$cycles} visits)"
    else
        puts "\nCongratualtions, you may all go free (took #{$cycles} visits)"
    end

    exit
end


class Prisoner

    def initialize(name)
        @name = name
        @i_have_previously_touched_a = false
    end

    def name
        return @name
    end

    def i_have_previously_touched_a
        return @i_have_previously_touched_a
    end

    def inspect
        return "Prisoner<#{@name}, #{@i_have_previously_touched_a}>"
    end

    def to_s
        return inspect
    end

    def switch_time(a_state, b_state)
        if a_state == false and !@i_have_previously_touched_a then
            @i_have_previously_touched_a = true
            return 'A'
        else
            return 'B'
        end
    end

end


class Watchkeeper < Prisoner

    def initialize
        @name = "Watchkeeper"
        @i_have_previously_touched_a = false
        @num_prisoners_touched_a = 0
    end

    def switch_time(a_state, b_state)
        if a_state == true
            @num_prisoners_touched_a += 1
            @i_have_previously_touched_a = true

            puts "Number of people who have switched 'A' is #{@num_prisoners_touched_a}"

            if @num_prisoners_touched_a == ($TOTAL_NUM_PRISONERS-1)
                puts "I declare we have all visited this room!"
                we_have_all_visited()
            end

            return 'A'
        else
            return 'B'
        end
    end
end

# Throw prisoners in jail
prisoners = Array.new
for i in 1 .. $TOTAL_NUM_PRISONERS-1
    prisoners.push(Prisoner.new("Prisoner #{i}"))
end
prisoners.push(Watchkeeper.new)


puts "Welcome to the prisoner's dilema"
puts "================================\n\n"

while true
    next_prisoner = rand(0 .. $TOTAL_NUM_PRISONERS-1)
    pr = prisoners[next_prisoner]

    puts "Current state of the switches: A=#{$switch_a}, B=#{$switch_b}"
    puts "#{pr.name}, you're up!"
    puts "#{pr.name}, have you previously touched A? #{pr.i_have_previously_touched_a}"

    choice = pr.switch_time($switch_a, $switch_b)
    puts "#{pr.name} chose #{choice}\n\n"

    if choice == 'A'
        $switch_a = !$switch_a
    else
        $switch_b = !$switch_b
    end

    $prisoners_who_have_visited[next_prisoner] = true

    $cycles += 1

    #gets
end