解24点

24.rb

def calculator number, *factors
	if factors.size == 1
		if number.to_f.round(10) == factors[0].to_f.round(10)
			return factors[0].to_s
		else
			return nil # nil stand for no solution
		end
	else
		factors.each_with_index do |factor, idx|
			[[:+, :-], [:-, :+], [:*, :/], [:/, :*]].each do |operator|
				temp_nmuber = number.send(operator[0], factor.to_f)
				temp_factors = factors.clone
				temp_factors.delete_at(idx)
				return "(#{calculator(temp_nmuber, * temp_factors)} #{operator[1]} #{factor})" if !calculator(temp_nmuber, *temp_factors).nil?
				if operator[0] == :- or operator[0] == :/
					temp_nmuber = factor.send(operator[0], number.to_f)
					if !calculator(temp_nmuber, * temp_factors).nil?
						return "(#{factor} #{operator[0]} #{calculator(temp_nmuber, * temp_factors)})"
					end
				end
			end
		end
	end
	nil
end

#ret = calculator 3, 1, 2
ret = calculator 24, 3,3,8,8
#ret = calculator 24, 5,5,5,1

#ret = calculator 4.8, 5,5,1
puts ret