flatten_nested_arrays.rb

#!/usr/bin/env ruby

def rakesh_flatten(input, level = -1)
  result = []
  def result.recursive(input, level)
    input.each do |ele|
      if Array === ele && level != 0
        recursive(ele, level - 1)
      else
        self << ele
      end
    end
  end
  result.recursive(input, level)
  result
end


inputs = [
  [],
  [1],
  [1, 2, 3],
  [1, [2, 3]],
  [1,2,[3,4],5,[6,[7,8]],[9]]
]

inputs.each_with_index do |orig_array, i|
  print "#{i + 1}) "; print orig_array; puts
  dup_array = orig_array.dup
  flat_dup_array = dup_array.flatten
  flat_orig_array = rakesh_flatten(orig_array)
  print "Flattened original array: "; print flat_orig_array; puts
  print "Flattened duplicate array: "; print flat_dup_array; puts
  puts (flat_orig_array == flat_dup_array) ? "PASS" : "FAIL"
end