Added quicksort challenge.

sorting_searching/quick_sort/quick_sort_challenge.ipynb

@@ -0,0 +1,154 @@
+{
+ "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: Implement quick sort.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Pythonic-Code](#Pythonic-Code)"
+   ]
+  },
+  {
+   "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",
+    "* Is a naiive solution sufficient (ie not in-place)?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* Empty input -> []\n",
+    "* One element -> [element]\n",
+    "* Two or more elements"
+   ]
+  },
+  {
+   "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": false
+   },
+   "outputs": [],
+   "source": [
+    "def quick_sort(data):\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_quick_sort.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestQuickSort(object):\n",
+    "    def test_quick_sort(self, func):\n",
+    "        print('Empty input')\n",
+    "        data = []\n",
+    "        func(data)\n",
+    "        assert_equal(data, [])\n",
+    "\n",
+    "        print('One element')\n",
+    "        data = [5]\n",
+    "        func(data)\n",
+    "        assert_equal(data, [5])\n",
+    "\n",
+    "        print('Two or more elements')\n",
+    "        data = [5, 1, 7, 2, 6, -3, 5, 7, -1]\n",
+    "        data = func(data)\n",
+    "        assert_equal(data, sorted(data))\n",
+    "        \n",
+    "        print('Success: test_quick_sort\\n')\n",
+    "\n",
+    "def main():\n",
+    "    test = TestQuickSort()\n",
+    "    test.test_quick_sort(quick_sort)\n",
+    "    try:\n",
+    "        test.test_quick_sort(quick_sort_alt)\n",
+    "    except NameError:\n",
+    "        # Alternate solutions are only defined\n",
+    "        # in the solutions file\n",
+    "        pass\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
+}

sorting_searching/quick_sort/quick_sort_solution.ipynb

@@ -29,7 +29,7 @@
     "\n",
     "*Problem statements are often intentionally ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
     "\n",
-    "* Are you looking for a naiive solution (ie not in-place)?\n",
+    "* Is a naiive solution sufficient (ie not in-place)?\n",
     "    * Yes"
    ]
   },
@@ -39,8 +39,8 @@
    "source": [
     "## Test Cases\n",
     "\n",
-    "* Empty input\n",
+    "* Empty input -> []\n",
-    "* One element\n",
+    "* One element -> [element]\n",
     "* Two or more elements"
    ]
   },
@@ -89,6 +89,8 @@
     "    right = []\n",
     "    pivot_index = len(data) / 2\n",
     "    pivot_value = data[pivot_index]\n",
+    "    \n",
+    "    # Build the left and right partitions\n",
     "    for i in xrange(0, len(data)):\n",
     "        if i == pivot_index:\n",
     "            continue\n",
@@ -96,6 +98,8 @@
     "            left.append(data[i])\n",
     "        else:\n",
     "            right.append(data[i])\n",
+    "            \n",
+    "    # Recursively apply quick_sort\n",
     "    left = quick_sort(left)\n",
     "    right = quick_sort(right)\n",
     "    return left + [pivot_value] + right"
@@ -145,23 +149,16 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Empty input\n",
+      "Overwriting test_quick_sort.py\n"
-      "One element\n",
-      "Two or more elements\n",
-      "Success: test_quick_sort\n",
-      "\n",
-      "Empty input\n",
-      "One element\n",
-      "Two or more elements\n",
-      "Success: test_quick_sort\n",
-      "\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_quick_sort.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestQuickSort(object):\n",
     "    def test_quick_sort(self, func):\n",
     "        print('Empty input')\n",
     "        data = []\n",
@@ -180,10 +177,46 @@
     "        \n",
     "        print('Success: test_quick_sort\\n')\n",
     "\n",
-    "if __name__ == '__main__':\n",
+    "def main():\n",
-    "    test = Test()\n",
+    "    test = TestQuickSort()\n",
     "    test.test_quick_sort(quick_sort)\n",
-    "    test.test_quick_sort(quick_sort_alt)"
+    "    try:\n",
+    "        test.test_quick_sort(quick_sort_alt)\n",
+    "    except NameError:\n",
+    "        # Alternate solutions are only defined\n",
+    "        # in the solutions file\n",
+    "        pass\n",
+    "        \n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Empty input\n",
+      "One element\n",
+      "Two or more elements\n",
+      "Success: test_quick_sort\n",
+      "\n",
+      "Empty input\n",
+      "One element\n",
+      "Two or more elements\n",
+      "Success: test_quick_sort\n",
+      "\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_quick_sort.py"
    ]
   }
  ],

sorting_searching/quick_sort/test_quick_sort.py

@@ -0,0 +1,34 @@
+from nose.tools import assert_equal
+
+
+class TestQuickSort(object):
+    def test_quick_sort(self, func):
+        print('Empty input')
+        data = []
+        func(data)
+        assert_equal(data, [])
+
+        print('One element')
+        data = [5]
+        func(data)
+        assert_equal(data, [5])
+
+        print('Two or more elements')
+        data = [5, 1, 7, 2, 6, -3, 5, 7, -1]
+        data = func(data)
+        assert_equal(data, sorted(data))
+        
+        print('Success: test_quick_sort\n')
+
+def main():
+    test = TestQuickSort()
+    test.test_quick_sort(quick_sort)
+    try:
+        test.test_quick_sort(quick_sort_alt)
+    except NameError:
+        # Alternate solutions are only defined
+        # in the solutions file
+        pass
+        
+if __name__ == '__main__':
+    main()