darts.rb

trials = 1000000
events = 0
trials.times do
	coords = 8.times.map { [rand, rand] }
	squares = coords.map { |x,y| [(x/0.25).ceil, (y/0.25).ceil] }
	unless squares.inject(Hash.new(0)) { |total, e| total[e] += 1 ;total}.select{|k,v| v>=3}.count.zero?
		events += 1
	end
end
puts events.to_f / trials.to_f