Added palindrome challenge.

linked_lists/palindrome/palindrome_challenge.ipynb

@@ -0,0 +1,184 @@
+{
+ "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: Determine if a linked list is a palindrome.\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",
+    "* Is a single character or number a palindrome?\n",
+    "    * No\n",
+    "* Can we assume we already have a linked list class that can be used for this problem?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "\n",
+    "* Empty list -> False\n",
+    "* Single element list -> False\n",
+    "* Two or more element list, not a palindrome -> False\n",
+    "* General case: Palindrome with even length -> True\n",
+    "* General case: Palindrome with odd length -> True"
+   ]
+  },
+  {
+   "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": [
+    "%run ../linked_list/linked_list.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "class MyLinkedList(LinkedList):\n",
+    "    \n",
+    "    def is_palindrome(self):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "*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.*"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "# %load test_palindrome.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestPalindrome(object):\n",
+    "    \n",
+    "    def test_palindrome(self):\n",
+    "        print('Test: Empty list')\n",
+    "        linked_list = MyLinkedList()\n",
+    "        assert_equal(linked_list.is_palindrome(), False)\n",
+    "\n",
+    "        print('Test: Single element list')\n",
+    "        head = Node(1)\n",
+    "        linked_list = MyLinkedList(head)\n",
+    "        assert_equal(linked_list.is_palindrome(), False)\n",
+    "\n",
+    "        print('Test: Two element list, not a palindrome')\n",
+    "        linked_list.append(2)\n",
+    "        assert_equal(linked_list.is_palindrome(), False)\n",
+    "\n",
+    "        print('Test: General case: Palindrome with even length')\n",
+    "        head = Node('a')\n",
+    "        linked_list = MyLinkedList(head)\n",
+    "        linked_list.append('b')\n",
+    "        linked_list.append('b')\n",
+    "        linked_list.append('a')\n",
+    "        assert_equal(linked_list.is_palindrome(), True)\n",
+    "\n",
+    "        print('Test: General case: Palindrome with odd length')\n",
+    "        head = Node(1)\n",
+    "        linked_list = MyLinkedList(head)\n",
+    "        linked_list.append(2)\n",
+    "        linked_list.append(3)\n",
+    "        linked_list.append(2)\n",
+    "        linked_list.append(1)\n",
+    "        assert_equal(linked_list.is_palindrome(), True)\n",
+    "        \n",
+    "        print('Success: test_palindrome')\n",
+    "\n",
+    "def main():\n",
+    "    test = TestPalindrome()\n",
+    "    test.test_palindrome()\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
+}

linked_lists/palindrome/palindrome_solution.ipynb

@@ -41,12 +41,11 @@
     "## Test Cases\n",
     "\n",
     "\n",
-    "* Empty list\n",
+    "* Empty list -> False\n",
-    "* Single element list\n",
+    "* Single element list -> False\n",
-    "* Two element list, not a palindrome\n",
+    "* Two or more element list, not a palindrome -> False\n",
-    "* Three element list, not a palindrome\n",
+    "* General case: Palindrome with even length -> True\n",
-    "* General case: Palindrome with even length\n",
+    "* General case: Palindrome with odd length -> True"
-    "* General case: Palindrome with odd length"
    ]
   },
   {
@@ -78,11 +77,11 @@
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
    "source": [
-    "%run linked_list.py"
+    "%run ../linked_list/linked_list.py"
    ]
   },
   {
@@ -94,6 +93,7 @@
    "outputs": [],
    "source": [
     "class MyLinkedList(LinkedList):\n",
+    "    \n",
     "    def is_palindrome(self):\n",
     "        if self.head is None or self.head.next is None:\n",
     "            return False\n",
@@ -145,21 +145,18 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Empty list\n",
+      "Overwriting test_palindrome.py\n"
-      "Test: Single element list\n",
-      "Test: Two element list, not a palindrome\n",
-      "Test: Three element list, not a palindrome\n",
-      "Test: General case: Palindrome with even length\n",
-      "Test: General case: Palindrome with odd length\n",
-      "Success: test_is_palindrome\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_palindrome.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
-    "    def test_is_palindrome(self):\n",
+    "class TestPalindrome(object):\n",
+    "    \n",
+    "    def test_palindrome(self):\n",
     "        print('Test: Empty list')\n",
     "        linked_list = MyLinkedList()\n",
     "        assert_equal(linked_list.is_palindrome(), False)\n",
@@ -173,10 +170,6 @@
     "        linked_list.append(2)\n",
     "        assert_equal(linked_list.is_palindrome(), False)\n",
     "\n",
-    "        print('Test: Three element list, not a palindrome')\n",
-    "        linked_list.append(3)\n",
-    "        assert_equal(linked_list.is_palindrome(), False)\n",
-    "\n",
     "        print('Test: General case: Palindrome with even length')\n",
     "        head = Node('a')\n",
     "        linked_list = MyLinkedList(head)\n",
@@ -194,11 +187,38 @@
     "        linked_list.append(1)\n",
     "        assert_equal(linked_list.is_palindrome(), True)\n",
     "        \n",
-    "        print('Success: test_is_palindrome')\n",
+    "        print('Success: test_palindrome')\n",
+    "\n",
+    "def main():\n",
+    "    test = TestPalindrome()\n",
+    "    test.test_palindrome()\n",
     "\n",
     "if __name__ == '__main__':\n",
-    "    test = Test()\n",
+    "    main()"
-    "    test.test_is_palindrome()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Empty list\n",
+      "Test: Single element list\n",
+      "Test: Two element list, not a palindrome\n",
+      "Test: General case: Palindrome with even length\n",
+      "Test: General case: Palindrome with odd length\n",
+      "Success: test_palindrome\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_palindrome.py"
    ]
   }
  ],

linked_lists/palindrome/test_palindrome.py

@@ -0,0 +1,44 @@
+from nose.tools import assert_equal
+
+
+class TestPalindrome(object):
+    
+    def test_palindrome(self):
+        print('Test: Empty list')
+        linked_list = MyLinkedList()
+        assert_equal(linked_list.is_palindrome(), False)
+
+        print('Test: Single element list')
+        head = Node(1)
+        linked_list = MyLinkedList(head)
+        assert_equal(linked_list.is_palindrome(), False)
+
+        print('Test: Two element list, not a palindrome')
+        linked_list.append(2)
+        assert_equal(linked_list.is_palindrome(), False)
+
+        print('Test: General case: Palindrome with even length')
+        head = Node('a')
+        linked_list = MyLinkedList(head)
+        linked_list.append('b')
+        linked_list.append('b')
+        linked_list.append('a')
+        assert_equal(linked_list.is_palindrome(), True)
+
+        print('Test: General case: Palindrome with odd length')
+        head = Node(1)
+        linked_list = MyLinkedList(head)
+        linked_list.append(2)
+        linked_list.append(3)
+        linked_list.append(2)
+        linked_list.append(1)
+        assert_equal(linked_list.is_palindrome(), True)
+        
+        print('Success: test_palindrome')
+
+def main():
+    test = TestPalindrome()
+    test.test_palindrome()
+
+if __name__ == '__main__':
+    main()