From 4c2c1d4391b340a0892a676c637e5f34e5712bff Mon Sep 17 00:00:00 2001 From: Donne Martin Date: Thu, 2 Jul 2015 23:09:53 -0400 Subject: [PATCH] Added delete mid challenge. --- linked_lists/delete_mid/__init__.py | 0 .../delete_mid/delete_mid_challenge.ipynb | 192 ++++++++++++++++++ .../delete_mid/delete_mid_solution.ipynb | 75 ++++--- linked_lists/delete_mid/test_delete_mid.py | 34 ++++ 4 files changed, 274 insertions(+), 27 deletions(-) create mode 100644 linked_lists/delete_mid/__init__.py create mode 100644 linked_lists/delete_mid/delete_mid_challenge.ipynb create mode 100644 linked_lists/delete_mid/test_delete_mid.py diff --git a/linked_lists/delete_mid/__init__.py b/linked_lists/delete_mid/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/linked_lists/delete_mid/delete_mid_challenge.ipynb b/linked_lists/delete_mid/delete_mid_challenge.ipynb new file mode 100644 index 0000000..4d25ddd --- /dev/null +++ b/linked_lists/delete_mid/delete_mid_challenge.ipynb @@ -0,0 +1,192 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges)." + ] + }, + { + "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 +} diff --git a/linked_lists/delete_mid/delete_mid_solution.ipynb b/linked_lists/delete_mid/delete_mid_solution.ipynb index 79d86dc..2791334 100644 --- a/linked_lists/delete_mid/delete_mid_solution.ipynb +++ b/linked_lists/delete_mid/delete_mid_solution.ipynb @@ -4,7 +4,14 @@ "cell_type": "markdown", "metadata": {}, "source": [ - "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes)." + "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges)." + ] + }, + { + "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", - "* Null node to delete\n", - "* One node\n", - "* Multiple nodes" + "* Delete on empty list -> None\n", + "* Delete None -> None\n", + "* Delete on one node -> [None]\n", + "* 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", - "Test: One node\n", - "Test: Multiple nodes\n", - "Success: test_delete_node\n" + "Overwriting test_delete_mid.py\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", - " test.test_delete_node()" + " main()" + ] + }, + { + "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" ] } ], diff --git a/linked_lists/delete_mid/test_delete_mid.py b/linked_lists/delete_mid/test_delete_mid.py new file mode 100644 index 0000000..7820e8f --- /dev/null +++ b/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() \ No newline at end of file