From 1d9e3ad49567d31504b8edf38e6385aae4980e07 Mon Sep 17 00:00:00 2001 From: Donne Martin Date: Thu, 2 Jul 2015 23:05:10 -0400 Subject: [PATCH] Added queue challenge. --- stacks_queues/queue_list/__init__.py | 0 stacks_queues/queue_list/queue_list.py | 6 +- .../queue_list/queue_list_challenge.ipynb | 217 ++++++++++++++++++ .../queue_list/queue_list_solution.ipynb | 66 ++++-- stacks_queues/queue_list/test_queue_list.py | 36 +++ 5 files changed, 305 insertions(+), 20 deletions(-) create mode 100644 stacks_queues/queue_list/__init__.py create mode 100644 stacks_queues/queue_list/queue_list_challenge.ipynb create mode 100644 stacks_queues/queue_list/test_queue_list.py diff --git a/stacks_queues/queue_list/__init__.py b/stacks_queues/queue_list/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/stacks_queues/queue_list/queue_list.py b/stacks_queues/queue_list/queue_list.py index c73339f..7df7bfb 100644 --- a/stacks_queues/queue_list/queue_list.py +++ b/stacks_queues/queue_list/queue_list.py @@ -1,12 +1,11 @@ -# Need to avoid naming this queue.py as it -# will conflict with IPython Notebook - class Node(object): + def __init__(self, data): self.data = data self.next = None class Queue(object): + def __init__(self): self.first = None self.last = None @@ -24,6 +23,7 @@ class Queue(object): # Empty list if self.first is None and self.last is None: return None + # Remove only element from a one element list elif self.first == self.last: data = self.first.data diff --git a/stacks_queues/queue_list/queue_list_challenge.ipynb b/stacks_queues/queue_list/queue_list_challenge.ipynb new file mode 100644 index 0000000..49a505f --- /dev/null +++ b/stacks_queues/queue_list/queue_list_challenge.ipynb @@ -0,0 +1,217 @@ +{ + "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: Implement a queue with enqueue and dequeue methods using a linked list.\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)\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", + "* If there is one item in the list, do you expect the first and last pointers to both point to it?\n", + " * Yes\n", + "* If there are no items on the list, do you expect the first and last pointers to be NULL?\n", + " * Yes\n", + "* If you dequeue on an empty queue, does that return None?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "### Enqueue\n", + "\n", + "* Enqueue to an empty queue\n", + "* Enqueue to a non-empty queue\n", + "\n", + "### Dequeue\n", + "\n", + "* Dequeue an empty queue -> None\n", + "* Dequeue a queue with one element\n", + "* Dequeue a queue with more than one element" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/queue_list/queue_list_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": [ + "class Node(object):\n", + " \n", + " def __init__(self, data):\n", + " self.data = data\n", + " self.next = None\n", + "\n", + "class Queue(object):\n", + " \n", + " def __init__(self):\n", + " self.first = None\n", + " self.last = None\n", + "\n", + " def enqueue(self, data):\n", + " node = Node(data)\n", + " if self.first is None and self.last is None:\n", + " self.first = node\n", + " self.last = node\n", + " else:\n", + " self.last.next = node\n", + " self.last = node\n", + "\n", + " def dequeue(self):\n", + " # Empty list\n", + " if self.first is None and self.last is None:\n", + " return None\n", + " \n", + " # Remove only element from a one element list\n", + " elif self.first == self.last:\n", + " data = self.first.data\n", + " self.first = None\n", + " self.last = None\n", + " return data\n", + " else:\n", + " data = self.first.data\n", + " self.first = self.first.next\n", + " return data" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Unit Test\n", + "\n", + "\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_queue_list.py\n", + "from nose.tools import assert_equal\n", + "\n", + "\n", + "class TestQueue(object):\n", + " \n", + " # TODO: It would be better if we had unit tests for each\n", + " # method in addition to the following end-to-end test\n", + " def test_end_to_end(self):\n", + " print('Test: Dequeue an empty queue')\n", + " queue = Queue()\n", + " assert_equal(queue.dequeue(), None)\n", + "\n", + " print('Test: Enqueue to an empty queue')\n", + " queue.enqueue(1)\n", + "\n", + " print('Test: Dequeue a queue with one element')\n", + " assert_equal(queue.dequeue(), 1)\n", + "\n", + " print('Test: Enqueue to a non-empty queue')\n", + " queue.enqueue(2)\n", + " queue.enqueue(3)\n", + " queue.enqueue(4)\n", + "\n", + " print('Test: Dequeue a queue with more than one element')\n", + " assert_equal(queue.dequeue(), 2)\n", + " assert_equal(queue.dequeue(), 3)\n", + " assert_equal(queue.dequeue(), 4)\n", + " \n", + " print('Success: test_end_to_end')\n", + "\n", + "def main():\n", + " test = TestQueue()\n", + " test.test_end_to_end()\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/stacks_queues/queue_list/queue_list_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/stacks_queues/queue_list/queue_list_solution.ipynb b/stacks_queues/queue_list/queue_list_solution.ipynb index 042fdfb..1130adf 100644 --- a/stacks_queues/queue_list/queue_list_solution.ipynb +++ b/stacks_queues/queue_list/queue_list_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" ] }, { @@ -27,11 +34,13 @@ "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", "* If there is one item in the list, do you expect the first and last pointers to both point to it?\n", " * Yes\n", "* If there are no items on the list, do you expect the first and last pointers to be NULL?\n", + " * Yes\n", + "* If you dequeue on an empty queue, does that return None?\n", " * Yes" ] }, @@ -48,7 +57,7 @@ "\n", "### Dequeue\n", "\n", - "* Dequeue an empty queue\n", + "* Dequeue an empty queue -> None\n", "* Dequeue a queue with one element\n", "* Dequeue a queue with more than one element" ] @@ -109,15 +118,14 @@ ], "source": [ "%%writefile queue_list.py\n", - "# Need to avoid naming this queue.py as it \n", - "# will conflict with IPython Notebook\n", - "\n", "class Node(object):\n", + " \n", " def __init__(self, data):\n", " self.data = data\n", " self.next = None\n", "\n", "class Queue(object):\n", + " \n", " def __init__(self):\n", " self.first = None\n", " self.last = None\n", @@ -164,8 +172,7 @@ "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" ] }, { @@ -179,19 +186,17 @@ "name": "stdout", "output_type": "stream", "text": [ - "Test: Dequeue an empty queue\n", - "Test: Enqueue to an empty queue\n", - "Test: Dequeue a queue with one element\n", - "Test: Enqueue to a non-empty queue\n", - "Test: Dequeue a queue with more than one element\n", - "Success: test_end_to_end\n" + "Overwriting test_queue_list.py\n" ] } ], "source": [ + "%%writefile test_queue_list.py\n", "from nose.tools import assert_equal\n", "\n", - "class Test(object):\n", + "\n", + "class TestQueue(object):\n", + " \n", " # TODO: It would be better if we had unit tests for each\n", " # method in addition to the following end-to-end test\n", " def test_end_to_end(self):\n", @@ -217,9 +222,36 @@ " \n", " print('Success: test_end_to_end')\n", "\n", + "def main():\n", + " test = TestQueue()\n", + " test.test_end_to_end()\n", + " \n", "if __name__ == '__main__':\n", - " test = Test()\n", - " test.test_end_to_end()" + " main()" + ] + }, + { + "cell_type": "code", + "execution_count": 4, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Test: Dequeue an empty queue\n", + "Test: Enqueue to an empty queue\n", + "Test: Dequeue a queue with one element\n", + "Test: Enqueue to a non-empty queue\n", + "Test: Dequeue a queue with more than one element\n", + "Success: test_end_to_end\n" + ] + } + ], + "source": [ + "%run -i test_queue_list.py" ] }, { diff --git a/stacks_queues/queue_list/test_queue_list.py b/stacks_queues/queue_list/test_queue_list.py new file mode 100644 index 0000000..e8429ac --- /dev/null +++ b/stacks_queues/queue_list/test_queue_list.py @@ -0,0 +1,36 @@ +from nose.tools import assert_equal + + +class TestQueue(object): + + # TODO: It would be better if we had unit tests for each + # method in addition to the following end-to-end test + def test_end_to_end(self): + print('Test: Dequeue an empty queue') + queue = Queue() + assert_equal(queue.dequeue(), None) + + print('Test: Enqueue to an empty queue') + queue.enqueue(1) + + print('Test: Dequeue a queue with one element') + assert_equal(queue.dequeue(), 1) + + print('Test: Enqueue to a non-empty queue') + queue.enqueue(2) + queue.enqueue(3) + queue.enqueue(4) + + print('Test: Dequeue a queue with more than one element') + assert_equal(queue.dequeue(), 2) + assert_equal(queue.dequeue(), 3) + assert_equal(queue.dequeue(), 4) + + print('Success: test_end_to_end') + +def main(): + test = TestQueue() + test.test_end_to_end() + +if __name__ == '__main__': + main() \ No newline at end of file