Added stack sorting challenge.

stacks_queues/sort_stack/sort_stack_challenge.ipynb

@@ -0,0 +1,177 @@
+{
+ "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://bit.ly/code-notes).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Sort a stack.  You can use another stack as a buffer.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "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",
+    "\n",
+    "* When sorted, should the largest element be at the top or bottom?\n",
+    "    * Top\n",
+    "* Can you have duplicate values like 5, 5?\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",
+    "* Empty stack -> None\n",
+    "* One element stack\n",
+    "* Two or more element stack (general case)\n",
+    "* Already sorted stack"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "Refer to the solution notebook.  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": true
+   },
+   "outputs": [],
+   "source": [
+    "%run ../stack/stack.py\n",
+    "%load ../stack/stack.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "class MyStack(Stack):\n",
+    "    \n",
+    "    def sort(self):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "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",
+    "\n",
+    "**The following unit test is expected to fail until you solve the challenge.**"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "# %load test_sort_stack.py\n",
+    "from random import randint\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestSortStack(object):\n",
+    "    \n",
+    "    def get_sorted_stack(self, numbers):\n",
+    "        stack = MyStack()\n",
+    "        for x in numbers:\n",
+    "            stack.push(x)\n",
+    "        sorted_stack = stack.sort()\n",
+    "        return sorted_stack\n",
+    "\n",
+    "    def test_sort_stack(self):\n",
+    "        print('Test: Empty stack')\n",
+    "        sorted_stack = self.get_sorted_stack([])\n",
+    "        assert_equal(sorted_stack.pop(), None)\n",
+    "\n",
+    "        print('Test: One element stack')\n",
+    "        sorted_stack = self.get_sorted_stack([1])\n",
+    "        assert_equal(sorted_stack.pop(), 1)\n",
+    "\n",
+    "        print('Test: Two or more element stack (general case)')\n",
+    "        num_items = 10\n",
+    "        numbers = [randint(0, 10) for x in xrange(num_items)]\n",
+    "        sorted_stack = self.get_sorted_stack(numbers)\n",
+    "        sorted_numbers = []\n",
+    "        for _ in xrange(num_items):\n",
+    "            sorted_numbers.append(sorted_stack.pop())\n",
+    "        assert_equal(sorted_numbers, sorted(numbers, reverse=True))\n",
+    "        \n",
+    "        print('Success: test_sort_stack')\n",
+    "\n",
+    "def main():\n",
+    "    test = TestSortStack()\n",
+    "    test.test_sort_stack()\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  }
+ ],
+ "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/sort_stack/sort_stack_solution.ipynb

@@ -42,7 +42,7 @@
    "source": [
     "## Test Cases\n",
     "\n",
-    "* Empty stack\n",
+    "* Empty stack -> None\n",
     "* One element stack\n",
     "* Two or more element stack (general case)\n",
     "* Already sorted stack"
@@ -82,7 +82,8 @@
    },
    "outputs": [],
    "source": [
-    "%run stack.py"
+    "%run ../stack/stack.py\n",
+    "%load ../stack/stack.py"
    ]
   },
   {
@@ -94,6 +95,7 @@
    "outputs": [],
    "source": [
     "class MyStack(Stack):\n",
+    "    \n",
     "    def sort(self):\n",
     "        buff = MyStack()\n",
     "        while not self.is_empty():\n",
@@ -124,18 +126,18 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Empty stack\n",
+      "Overwriting test_sort_stack.py\n"
-      "Test: One element stack\n",
-      "Test: Two or more element stack (general case)\n",
-      "Success: test_sort_stack\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_sort_stack.py\n",
     "from random import randint\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestSortStack(object):\n",
+    "    \n",
     "    def get_sorted_stack(self, numbers):\n",
     "        stack = MyStack()\n",
     "        for x in numbers:\n",
@@ -163,9 +165,34 @@
     "        \n",
     "        print('Success: test_sort_stack')\n",
     "\n",
+    "def main():\n",
+    "    test = TestSortStack()\n",
+    "    test.test_sort_stack()\n",
+    "\n",
     "if __name__ == '__main__':\n",
-    "    test = Test()\n",
+    "    main()"
-    "    test.test_sort_stack()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Empty stack\n",
+      "Test: One element stack\n",
+      "Test: Two or more element stack (general case)\n",
+      "Success: test_sort_stack\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_sort_stack.py"
    ]
   }
  ],

stacks_queues/sort_stack/test_sort_stack.py

@@ -0,0 +1,39 @@
+from random import randint
+from nose.tools import assert_equal
+
+
+class TestSortStack(object):
+    
+    def get_sorted_stack(self, numbers):
+        stack = MyStack()
+        for x in numbers:
+            stack.push(x)
+        sorted_stack = stack.sort()
+        return sorted_stack
+
+    def test_sort_stack(self):
+        print('Test: Empty stack')
+        sorted_stack = self.get_sorted_stack([])
+        assert_equal(sorted_stack.pop(), None)
+
+        print('Test: One element stack')
+        sorted_stack = self.get_sorted_stack([1])
+        assert_equal(sorted_stack.pop(), 1)
+
+        print('Test: Two or more element stack (general case)')
+        num_items = 10
+        numbers = [randint(0, 10) for x in xrange(num_items)]
+        sorted_stack = self.get_sorted_stack(numbers)
+        sorted_numbers = []
+        for _ in xrange(num_items):
+            sorted_numbers.append(sorted_stack.pop())
+        assert_equal(sorted_numbers, sorted(numbers, reverse=True))
+        
+        print('Success: test_sort_stack')
+
+def main():
+    test = TestSortStack()
+    test.test_sort_stack()
+
+if __name__ == '__main__':
+    main()