flatten_array.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# Write some code in either Ruby or JavaScript that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers. e.g. [[1,2,[3]],4] -> [1,2,3,4]. Please don't use any built-in flatten functions in either language.\n"
   ]
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   "source": [
    "First, I would like to understand the example array given.\n",
    "\n",
    "Array `[[1,2,[3]],4]` consist of:\n",
    "\n",
    "```\n",
    "array = [subarray1,4]\n",
    "subarray1 = [1,2,subarray2]\n",
    "subarrary2 = [3]\n",
    "```\n",
    "\n",
    "So, I am thinking if there's a way to loop `array` items and if current item is an array, call the same function (like a recursive \n",
    "function)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
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    {
     "data": {
      "text/plain": [
       "[[1, 2, [3]], 4]"
      ]
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     "execution_count": 24,
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     "output_type": "execute_result"
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   "source": [
    "array = [[1,2,[3]],4]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Initially I would like to know if this function `is_a?` works"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
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   "outputs": [
    {
     "name": "stdout",
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     "text": [
      "found array: [1, 2, [3]]\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[[1, 2, [3]], 4]"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "array.each do |item|\n",
    "  if item.is_a? Array\n",
    "    puts(\"found array: #{item}\")\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So perhaps I could make a function that if item is an array, call itself. And I will need to store the result in new array."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {
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   "outputs": [
    {
     "data": {
      "text/plain": [
       ":make_array"
      ]
     },
     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "\n",
    "def make_array(result=[], array)\n",
    "  @result = result\n",
    "  puts(\"array is #{array}\")\n",
    "  array.each do |item|\n",
    "    if item.is_a? Array\n",
    "      puts(\"found array: #{item}\")\n",
    "      make_array(result, item)\n",
    "    else\n",
    "      result.push(item)\n",
    "    end\n",
    "  end\n",
    "  return result\n",
    "end\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
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     "output_type": "stream",
     "text": [
      "array is [[1, 2, [3]], 4]\n",
      "found array: [1, 2, [3]]\n",
      "array is [1, 2, [3]]\n",
      "found array: [3]\n",
      "array is [3]\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[1, 2, 3, 4]"
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "make_array array\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Cleaned code becomes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       ":make_array"
      ]
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def make_array(result=[], array)\n",
    "  @result = result\n",
    "  puts(\"array is #{array}\")\n",
    "  array.each do |item|\n",
    "    if item.is_a? Array\n",
    "      puts(\"found array: #{item}\")\n",
    "      make_array(result, item)\n",
    "    else\n",
    "      result.push(item)\n",
    "    end\n",
    "  end\n",
    "  return result\n",
    "end\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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