diff --git a/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_challenge.ipynb b/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_challenge.ipynb
index ec4abf3..2e37493 100644
--- a/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_challenge.ipynb
+++ b/recursion_dynamic/n_pairs_parentheses/n_pairs_parentheses_challenge.ipynb
@@ -18,7 +18,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Problem: Print all valid combinations of n-pairs of parentheses\n",
+    "## Problem: Print all valid combinations of n-pairs of parentheses.\n",
     "\n",
     "* [Constraints](#Constraints)\n",
     "* [Test Cases](#Test-Cases)\n",
@@ -48,6 +48,15 @@
     "* 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": {},
@@ -57,7 +66,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": null,
    "metadata": {
     "collapsed": true
    },
@@ -73,7 +82,7 @@
     "    if n == 0:\n",
     "        return result_set\n",
     "    parentheses_util(n, n, '', result_set)\n",
-    "    return result_set\n"
+    "    return result_set"
    ]
   },
   {
@@ -85,45 +94,36 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": null,
    "metadata": {
     "collapsed": false
    },
-   "outputs": [
-    {
-     "ename": "AssertionError",
-     "evalue": "Items in the second set but not the first:\n'()'",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
-      "\u001b[1;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
-      "\u001b[1;32m<ipython-input-2-11484e8ba6e9>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m     16\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     17\u001b[0m \u001b[1;32mif\u001b[0m \u001b[0m__name__\u001b[0m \u001b[1;33m==\u001b[0m \u001b[1;34m'__main__'\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 18\u001b[1;33m     \u001b[0mmain\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
-      "\u001b[1;32m<ipython-input-2-11484e8ba6e9>\u001b[0m in \u001b[0;36mmain\u001b[1;34m()\u001b[0m\n\u001b[0;32m     13\u001b[0m \u001b[1;32mdef\u001b[0m \u001b[0mmain\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     14\u001b[0m     \u001b[0mtest\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mTestPairParentheses\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 15\u001b[1;33m     \u001b[0mtest\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mtest_pair_parentheses\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mpair_parentheses\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m     16\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     17\u001b[0m \u001b[1;32mif\u001b[0m \u001b[0m__name__\u001b[0m \u001b[1;33m==\u001b[0m \u001b[1;34m'__main__'\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
-      "\u001b[1;32m<ipython-input-2-11484e8ba6e9>\u001b[0m in \u001b[0;36mtest_pair_parentheses\u001b[1;34m(self, solution)\u001b[0m\n\u001b[0;32m      6\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0mtest_pair_parentheses\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0msolution\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      7\u001b[0m         \u001b[0massert_equal\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m0\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mset\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 8\u001b[1;33m         \u001b[0massert_equal\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m1\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mset\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'()'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      9\u001b[0m         \u001b[0massert_equal\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m2\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mset\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'(())'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'()()'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     10\u001b[0m         \u001b[0massert_equal\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m3\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mset\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'((()))'\u001b[0m\u001b[1;33m,\u001b[0m\u001b[1;34m'(()())'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'(())()'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'()(())'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'()()()'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
-      "\u001b[1;32m/usr/lib/python2.7/unittest/case.py\u001b[0m in \u001b[0;36massertEqual\u001b[1;34m(self, first, second, msg)\u001b[0m\n\u001b[0;32m    511\u001b[0m         \"\"\"\n\u001b[0;32m    512\u001b[0m         \u001b[0massertion_func\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_getAssertEqualityFunc\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mfirst\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0msecond\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m--> 513\u001b[1;33m         \u001b[0massertion_func\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mfirst\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0msecond\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[1;33m=\u001b[0m\u001b[0mmsg\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m    514\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    515\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0massertNotEqual\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mfirst\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0msecond\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[1;33m=\u001b[0m\u001b[0mNone\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
-      "\u001b[1;32m/usr/lib/python2.7/unittest/case.py\u001b[0m in \u001b[0;36massertSetEqual\u001b[1;34m(self, set1, set2, msg)\u001b[0m\n\u001b[0;32m    794\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    795\u001b[0m         \u001b[0mstandardMsg\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;34m'\\n'\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mjoin\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mlines\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m--> 796\u001b[1;33m         \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mfail\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_formatMessage\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mmsg\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mstandardMsg\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m    797\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    798\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0massertIn\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmember\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mcontainer\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[1;33m=\u001b[0m\u001b[0mNone\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
-      "\u001b[1;32m/usr/lib/python2.7/unittest/case.py\u001b[0m in \u001b[0;36mfail\u001b[1;34m(self, msg)\u001b[0m\n\u001b[0;32m    408\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0mfail\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[1;33m=\u001b[0m\u001b[0mNone\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    409\u001b[0m         \u001b[1;34m\"\"\"Fail immediately, with the given message.\"\"\"\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m--> 410\u001b[1;33m         \u001b[1;32mraise\u001b[0m \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mfailureException\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mmsg\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m    411\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    412\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0massertFalse\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mexpr\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[1;33m=\u001b[0m\u001b[0mNone\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
-      "\u001b[1;31mAssertionError\u001b[0m: Items in the second set but not the first:\n'()'"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "# %load test_n_pairs_parentheses.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
+    "\n",
     "class TestPairParentheses(object):\n",
-    "    \n",
+    "\n",
     "    def test_pair_parentheses(self, solution):\n",
     "        assert_equal(solution(0), set([]))\n",
     "        assert_equal(solution(1), set(['()']))\n",
-    "        assert_equal(solution(2), set(['(())', '()()']))\n",
-    "        assert_equal(solution(3), set(['((()))','(()())', '(())()', '()(())', '()()()']))\n",
+    "        assert_equal(solution(2), set(['(())', \n",
+    "                                       '()()']))\n",
+    "        assert_equal(solution(3), set(['((()))', \n",
+    "                                       '(()())', \n",
+    "                                       '(())()', \n",
+    "                                       '()(())', \n",
+    "                                       '()()()']))\n",
     "        print('Success: test_pair_parentheses')\n",
     "\n",
+    "\n",
     "def main():\n",
     "    test = TestPairParentheses()\n",
     "    test.test_pair_parentheses(pair_parentheses)\n",
     "\n",
+    "\n",
     "if __name__ == '__main__':\n",
     "    main()"
    ]
@@ -134,8 +134,17 @@
    "source": [
     "## Solution Notebook\n",
     "\n",
-    "Review the [Solution Notebook](#) for a discussion on algorithms and code solutions."
+    "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."
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {
@@ -154,7 +163,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,