Flatten a Ruby Array without using built-in 'flatten' method [closed]

Answer 1

Using recursion to solve this problem.

class ArrayConvert
    def self.flatten_array(array,init)
        array.each do |a|
         if a.class==Array
            flatten_array(a,init)
         else
            init << a
         end
        end
      init
    end

  p flatten_array([1, 2, 3, 4, [1, 2, 3, 4], 5],[])

end

Answer 2

class Array
  def flattify
    each_with_object([]) do |element, flattened|
      flattened.push *(element.is_a?(Array) ? element.flattify : element)
    end
  end
end

[1,2,3,4,[1,2,3,4],5].flattify # => [1, 2, 3, 4, 1, 2, 3, 4, 5]

---

A non-monkey patching Array version:

def flattify(array)
  array.each_with_object([]) do |element, flattened|
    flattened.push *(element.is_a?(Array) ? flattify(element) : element)
  end
end

flattify([1,2,3,4,[1,2,3,4],5]) # => [1, 2, 3, 4, 1, 2, 3, 4, 5]