      "* 2 -> [(()), ()()]\n",
      "* 3 -> [((())), (()()), (())(), ()(()), ()()()]"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Code"
 
</s> remove     "## Problem: Print all valid combinations of n-pairs of parentheses\n",
 </s> add     "## Problem: Print all valid combinations of n-pairs of parentheses.\n", </s> remove     "    return result_set\n"
 </s> add     "    return result_set" </s> remove     "Review the [Solution Notebook](#) for a discussion on algorithms and code solutions."
 </s> add     "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_solution.ipynb) for a discussion on algorithms and code solutions." </s> remove    "execution_count": 1,
 </s> add    "execution_count": null, </s> remove    "execution_count": 2,
 </s> add    "execution_count": null,
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Algorithm\n",
    "\n",
    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_solution.ipynb).  If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
   ]
  },
      "* 2 -> [(()), ()()]\n",
      "* 3 -> [((())), (()()), (())(), ()(()), ()()()]"
     ]
    },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Algorithm\n",
    "\n",
    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_solution.ipynb).  If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
   ]
  },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Code"
keep keep keep add keep keep keep keep keep
 Cleaned up n pairs parentheses challenge notebook. 
recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_challenge.ipynb