Added delete mid challenge.

linked_lists/delete_mid/delete_mid_challenge.ipynb

@@ -0,0 +1,192 @@
+{
+ "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: Delete a node in the middle, given only access to that node.\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",
+    "* What if the final node is being deleted, for example a single node list?  Do we make it a dummy with a NULL value?\n",
+    "    * Yes\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",
+    "* Delete on empty list -> None\n",
+    "* Delete None -> None\n",
+    "* Delete on one node -> [None]\n",
+    "* Delete on multiple nodes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/linked_lists/delete_mid/delete_mid_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 ../linked_list/linked_list.py\n",
+    "%load ../linked_list/linked_list.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "class MyLinkedList(LinkedList):\n",
+    "    \n",
+    "    def delete_node(self, node):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\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_delete_mid.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestDeleteNode(object):\n",
+    "    \n",
+    "    def test_delete_node(self):\n",
+    "        print('Test: Empty list, null node to delete')\n",
+    "        linked_list = MyLinkedList(None)\n",
+    "        linked_list.delete_node(None)\n",
+    "        assert_equal(linked_list.get_all_data(), [])\n",
+    "\n",
+    "        print('Test: One node')\n",
+    "        head = Node(2)\n",
+    "        linked_list = MyLinkedList(head)\n",
+    "        linked_list.delete_node(head)\n",
+    "        assert_equal(linked_list.get_all_data(), [None])\n",
+    "\n",
+    "        print('Test: Multiple nodes')\n",
+    "        linked_list = MyLinkedList(None)        \n",
+    "        node0 = linked_list.insert_to_front(1)\n",
+    "        node1 = linked_list.insert_to_front(3)\n",
+    "        node2 = linked_list.insert_to_front(4)\n",
+    "        node3 = linked_list.insert_to_front(1)\n",
+    "        linked_list.delete_node(node2)\n",
+    "        assert_equal(linked_list.get_all_data(), [1, 3, 1])\n",
+    "        \n",
+    "        print('Success: test_delete_node')\n",
+    "\n",
+    "def main():\n",
+    "    test = TestDeleteNode()\n",
+    "    test.test_delete_node()\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/linked_lists/delete_mid/delete_mid_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
+}

linked_lists/delete_mid/delete_mid_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",
     "* What if the final node is being deleted, for example a single node list?  Do we make it a dummy with a NULL value?\n",
     "    * Yes\n",
@@ -40,10 +47,10 @@
    "source": [
     "## Test Cases\n",
     "\n",
-    "* Empty list\n",
+    "* Delete on empty list -> None\n",
-    "* Null node to delete\n",
+    "* Delete None -> None\n",
-    "* One node\n",
+    "* Delete on one node -> [None]\n",
-    "* Multiple nodes"
+    "* Delete on multiple nodes"
    ]
   },
   {
@@ -74,11 +81,11 @@
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
    "source": [
-    "%run linked_list.py"
+    "%run ../linked_list/linked_list.py"
    ]
   },
   {
@@ -89,12 +96,8 @@
    },
    "outputs": [],
    "source": [
-    "class Node(object):\n",
-    "    def __init__(self, data):\n",
-    "        self.data = data\n",
-    "        self.next = None\n",
-    "\n",
     "class MyLinkedList(LinkedList):\n",
+    "    \n",
     "    def delete_node(self, node):\n",
     "        if self.head is None:\n",
     "            return\n",
@@ -116,13 +119,6 @@
     "## 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": 3,
@@ -134,17 +130,17 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Empty list, null node to delete\n",
+      "Overwriting test_delete_mid.py\n"
-      "Test: One node\n",
-      "Test: Multiple nodes\n",
-      "Success: test_delete_node\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_delete_mid.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestDeleteNode(object):\n",
+    "    \n",
     "    def test_delete_node(self):\n",
     "        print('Test: Empty list, null node to delete')\n",
     "        linked_list = MyLinkedList(None)\n",
@@ -168,9 +164,34 @@
     "        \n",
     "        print('Success: test_delete_node')\n",
     "\n",
+    "def main():\n",
+    "    test = TestDeleteNode()\n",
+    "    test.test_delete_node()\n",
+    "    \n",
     "if __name__ == '__main__':\n",
-    "    test = Test()\n",
+    "    main()"
-    "    test.test_delete_node()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Empty list, null node to delete\n",
+      "Test: One node\n",
+      "Test: Multiple nodes\n",
+      "Success: test_delete_node\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_delete_mid.py"
    ]
   }
  ],

linked_lists/delete_mid/test_delete_mid.py

@@ -0,0 +1,34 @@
+from nose.tools import assert_equal
+
+
+class TestDeleteNode(object):
+    
+    def test_delete_node(self):
+        print('Test: Empty list, null node to delete')
+        linked_list = MyLinkedList(None)
+        linked_list.delete_node(None)
+        assert_equal(linked_list.get_all_data(), [])
+
+        print('Test: One node')
+        head = Node(2)
+        linked_list = MyLinkedList(head)
+        linked_list.delete_node(head)
+        assert_equal(linked_list.get_all_data(), [None])
+
+        print('Test: Multiple nodes')
+        linked_list = MyLinkedList(None)        
+        node0 = linked_list.insert_to_front(1)
+        node1 = linked_list.insert_to_front(3)
+        node2 = linked_list.insert_to_front(4)
+        node3 = linked_list.insert_to_front(1)
+        linked_list.delete_node(node2)
+        assert_equal(linked_list.get_all_data(), [1, 3, 1])
+        
+        print('Success: test_delete_node')
+
+def main():
+    test = TestDeleteNode()
+    test.test_delete_node()
+    
+if __name__ == '__main__':
+    main()