Added queue from stacks challenge.

stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb

@@ -4,7 +4,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Solution Notebook"
    ]
   },
   {
@@ -26,7 +33,7 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "*Problem statements are often intentionally ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
+    "*Problem statements are sometimes ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
     "\n",
     "* Do you expect the methods to be enqueue and dequeue?\n",
     "    * Yes\n",
@@ -99,11 +106,11 @@
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
    "source": [
-    "%run stack.py"
+    "%run ../stack/stack.py"
    ]
   },
   {
@@ -115,6 +122,7 @@
    "outputs": [],
    "source": [
     "class QueueFromStacks(object):\n",
+    "    \n",
     "    def __init__(self):\n",
     "        self.left_stack = Stack()\n",
     "        self.right_stack = Stack()\n",
@@ -139,8 +147,7 @@
    "metadata": {},
    "source": [
     "## Unit Test\n",
-    "\n",
-    "*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand.  You generally will not be asked to write a unit test like what is shown below.*"
+    "\n"
    ]
   },
   {
@@ -154,22 +161,17 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Dequeue on empty stack\n",
-      "Test: Enqueue on empty stack\n",
-      "Test: Enqueue on non-empty stack\n",
-      "Test: Multiple enqueue in a row\n",
-      "Test: Dequeue on non-empty stack\n",
-      "Test: Dequeue after an enqueue\n",
-      "Test: Multiple dequeue in a row\n",
-      "Test: Enqueue after a dequeue\n",
-      "Success: test_queue_from_stacks\n"
+      "Overwriting test_queue_from_stacks.py\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_queue_from_stacks.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestQueueFromStacks(object):\n",
+    "    \n",
     "    def test_queue_from_stacks(self):\n",
     "        print('Test: Dequeue on empty stack')\n",
     "        queue = QueueFromStacks()\n",
@@ -196,9 +198,39 @@
     "\n",
     "        print('Success: test_queue_from_stacks')\n",
     "\n",
+    "def main():\n",
+    "    test = TestQueueFromStacks()\n",
+    "    test.test_queue_from_stacks()\n",
+    "    \n",
     "if __name__ == '__main__':\n",
-    "    test = Test()\n",
-    "    test.test_queue_from_stacks()"
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Dequeue on empty stack\n",
+      "Test: Enqueue on empty stack\n",
+      "Test: Enqueue on non-empty stack\n",
+      "Test: Multiple enqueue in a row\n",
+      "Test: Dequeue on non-empty stack\n",
+      "Test: Dequeue after an enqueue\n",
+      "Test: Multiple dequeue in a row\n",
+      "Test: Enqueue after a dequeue\n",
+      "Success: test_queue_from_stacks\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_queue_from_stacks.py"
    ]
   }
  ],