Added queue from stacks challenge.

stacks_queues/queue_from_stacks/queue_from_stacks_challenge.ipynb

@@ -0,0 +1,201 @@
+{
+ "cells": [
+  {
+   "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://github.com/donnemartin/coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Challenge Notebook"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Implement a queue using two stacks.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Solution Notebook](#Solution-Notebook)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "\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",
+    "* Can we assume we already have a stack class that can be used for this problem?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* Enqueue and dequeue on empty stack\n",
+    "* Enqueue and dequeue on non-empty stack\n",
+    "* Multiple enqueue in a row\n",
+    "* Multiple dequeue in a row\n",
+    "* Enqueue after a dequeue\n",
+    "* Dequeue after an enqueue"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/queue_from_stacks/queue_from_stacks_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"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "%run ../stack/stack.py\n",
+    "%load ../stack/stack.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "class QueueFromStacks(object):\n",
+    "    \n",
+    "    def __init__(self):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def shift_stacks(self, source, destination):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def enqueue(self, data):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def dequeue(self):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test\n",
+    "\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "# %load test_queue_from_stacks.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestQueueFromStacks(object):\n",
+    "    \n",
+    "    def test_queue_from_stacks(self):\n",
+    "        print('Test: Dequeue on empty stack')\n",
+    "        queue = QueueFromStacks()\n",
+    "        assert_equal(queue.dequeue(), None)\n",
+    "\n",
+    "        print('Test: Enqueue on empty stack')\n",
+    "        print('Test: Enqueue on non-empty stack')\n",
+    "        print('Test: Multiple enqueue in a row')\n",
+    "        num_items = 3\n",
+    "        for i in range (0, num_items):\n",
+    "            queue.enqueue(i)\n",
+    "\n",
+    "        print('Test: Dequeue on non-empty stack')\n",
+    "        print('Test: Dequeue after an enqueue')\n",
+    "        assert_equal(queue.dequeue(), 0)\n",
+    "\n",
+    "        print('Test: Multiple dequeue in a row')\n",
+    "        assert_equal(queue.dequeue(), 1)\n",
+    "        assert_equal(queue.dequeue(), 2)\n",
+    "\n",
+    "        print('Test: Enqueue after a dequeue')\n",
+    "        queue.enqueue(5)\n",
+    "        assert_equal(queue.dequeue(), 5)\n",
+    "\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",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Solution Notebook\n",
+    "\n",
+    "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb) for a discussion on algorithms and code solutions."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}

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",
+    "\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.*"
    ]
   },
   {
@@ -154,22 +161,17 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Dequeue on empty stack\n",
+      "Overwriting test_queue_from_stacks.py\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": [
+    "%%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",
+    "    main()"
-    "    test.test_queue_from_stacks()"
+   ]
+  },
+  {
+   "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"
    ]
   }
  ],

stacks_queues/queue_from_stacks/test_queue_from_stacks.py

@@ -0,0 +1,37 @@
+from nose.tools import assert_equal
+
+
+class TestQueueFromStacks(object):
+    
+    def test_queue_from_stacks(self):
+        print('Test: Dequeue on empty stack')
+        queue = QueueFromStacks()
+        assert_equal(queue.dequeue(), None)
+
+        print('Test: Enqueue on empty stack')
+        print('Test: Enqueue on non-empty stack')
+        print('Test: Multiple enqueue in a row')
+        num_items = 3
+        for i in range (0, num_items):
+            queue.enqueue(i)
+
+        print('Test: Dequeue on non-empty stack')
+        print('Test: Dequeue after an enqueue')
+        assert_equal(queue.dequeue(), 0)
+
+        print('Test: Multiple dequeue in a row')
+        assert_equal(queue.dequeue(), 1)
+        assert_equal(queue.dequeue(), 2)
+
+        print('Test: Enqueue after a dequeue')
+        queue.enqueue(5)
+        assert_equal(queue.dequeue(), 5)
+
+        print('Success: test_queue_from_stacks')
+
+def main():
+    test = TestQueueFromStacks()
+    test.test_queue_from_stacks()
+    
+if __name__ == '__main__':
+    main()