Maximum product of subarray

def product_max(a)


  max_so_far = 1
  min_so_far = 1

  max = 1

  a.each do |i|

    if i == 0
      max_so_far = 1
      min_so_far = 1
    elsif i > 0
      max_so_far = max_so_far * i
      min_so_far = [min_so_far * i, 1].min
    else
      max_so_far = [min_so_far * i, 1].max
      min_so_far = max_so_far * i
    end

    if max_so_far > max
      max = max_so_far
    end


  end

  max

end