The Vietnamese third grade math problem in Ruby

gistfile1.rb

# The equation
def equation(a, b, c, d, e, f, g, h, i)
  a + 13 * b / c + d + 12 * e - f - 11 + g * h / i - 10
end

# The brute force
def solutions(*numbers)
  numbers.
  permutation.
  map { |nums| [nums, equation(*nums)] }.
  select { |nums, res| res == 66 }
end

# And some printouts
def print(solutions)
  solutions.each { |nums, res| puts "#{nums.inspect} == #{res}" }
  puts "#{solutions.size} solutions"
end

print(solutions(1, 2, 3, 4, 5, 6, 7, 8, 9))
print(solutions(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0))