    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Problem: Implement foo(val), which returns val\n",
      "\n",
      "* [Constraints](#Constraints)\n",
      "* [Test Cases](#Test-Cases)\n",
      "* [Algorithm](#Algorithm)\n",
      "* [Code](#Code)\n",
 
</s> remove     "* [Algorithm](#Algorithm)\n",
    "* [Code](#Code)\n",
 </s> add     "* [Algorithm: Modified Selection Sort](#Algorithm: Modified Selection Sort)\n",
    "* [Code: Modified Selection Sort](#Code: Modified Selection Sort)\n",
    "* [Algorithm: Ordered Dict](#Algorithm: Ordered Dict)\n",
    "* [Code: Ordered Dict](#Code:-Ordered-Dict)\n", </s> remove     "## Algorithm\n",
 </s> add     "## Algorithm: Modified Selection Sort\n", </s> remove     "* foo(val) -> val"
 </s> add     "* group_ordered([1,2,1,3,2]) -> [1,1,2,2,3]\n",
    "* group_ordered(['a','b','a') -> ['a','a','b']\n",
    "* group_ordered([1,1,2,3,4,5,2,1]-> [1,1,1,2,2,3,4,5]\n",
    "* group_ordered([]) -> []\n",
    "* group_ordered([1]) -> [1]\n",
    "* group_ordered(None) -> None\n" </s> remove     "* Time: O(1)\n",
    "* Space: O(1)"
 </s> add     "* Time: O(n^2)\n",
    "* Space: O(n)" </s> remove 
    "* Is it foo or bar?\n",
    "    * foo"
 </s> add     "* Can we use extra data structures?\n",
    "    * Yes"
    "## Problem: Implement a function that groups identical items based on their order in the list.\n",
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
    "## Problem: Implement a function that groups identical items based on their order in the list.\n",
      "\n",
      "* [Constraints](#Constraints)\n",
      "* [Test Cases](#Test-Cases)\n",
      "* [Algorithm](#Algorithm)\n",
      "* [Code](#Code)\n",
keep keep keep keep replace keep keep keep keep keep
 added both solutions w/ test 
arrays_strings/group_items/group_ordered_solution.ipynb