mirror of
https://github.com/donnemartin/interactive-coding-challenges
synced 2026-01-05 00:48:03 +00:00
Added queue challenge.
This commit is contained in:
Donne Martin
0
stacks_queues/queue_list/__init__.py
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0
stacks_queues/queue_list/__init__.py
Normal file
@@ -1,12 +1,11 @@
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# Need to avoid naming this queue.py as it
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# will conflict with IPython Notebook
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class Node(object):
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def __init__(self, data):
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self.data = data
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self.next = None
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class Queue(object):
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def __init__(self):
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self.first = None
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self.last = None
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@@ -24,6 +23,7 @@ class Queue(object):
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# Empty list
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if self.first is None and self.last is None:
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return None
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# Remove only element from a one element list
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elif self.first == self.last:
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data = self.first.data
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217
stacks_queues/queue_list/queue_list_challenge.ipynb
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217
stacks_queues/queue_list/queue_list_challenge.ipynb
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@@ -0,0 +1,217 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<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>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Challenge Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Implement a queue with enqueue and dequeue methods using a linked list.\n",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)\n",
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"* [Pythonic-Code](#Pythonic-Code)\n",
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"* [Solution Notebook](#Solution-Notebook)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints\n",
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"\n",
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"*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
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"\n",
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"* If there is one item in the list, do you expect the first and last pointers to both point to it?\n",
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" * Yes\n",
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"* If there are no items on the list, do you expect the first and last pointers to be NULL?\n",
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" * Yes\n",
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"* If you dequeue on an empty queue, does that return None?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"### Enqueue\n",
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"\n",
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"* Enqueue to an empty queue\n",
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"* Enqueue to a non-empty queue\n",
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"\n",
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"### Dequeue\n",
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"\n",
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"* Dequeue an empty queue -> None\n",
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"* Dequeue a queue with one element\n",
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"* Dequeue a queue with more than one element"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"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."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Node(object):\n",
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" \n",
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" def __init__(self, data):\n",
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" self.data = data\n",
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" self.next = None\n",
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"\n",
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"class Queue(object):\n",
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" \n",
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" def __init__(self):\n",
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" self.first = None\n",
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" self.last = None\n",
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"\n",
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" def enqueue(self, data):\n",
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" node = Node(data)\n",
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" if self.first is None and self.last is None:\n",
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" self.first = node\n",
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" self.last = node\n",
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" else:\n",
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" self.last.next = node\n",
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" self.last = node\n",
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"\n",
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" def dequeue(self):\n",
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" # Empty list\n",
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" if self.first is None and self.last is None:\n",
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" return None\n",
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" \n",
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" # Remove only element from a one element list\n",
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" elif self.first == self.last:\n",
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" data = self.first.data\n",
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" self.first = None\n",
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" self.last = None\n",
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" return data\n",
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" else:\n",
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" data = self.first.data\n",
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" self.first = self.first.next\n",
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" return data"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Unit Test\n",
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"\n",
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"\n",
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"\n",
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"**The following unit test is expected to fail until you solve the challenge.**"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"# %load test_queue_list.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"\n",
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"class TestQueue(object):\n",
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" \n",
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" # TODO: It would be better if we had unit tests for each\n",
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" # method in addition to the following end-to-end test\n",
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" def test_end_to_end(self):\n",
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" print('Test: Dequeue an empty queue')\n",
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" queue = Queue()\n",
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" assert_equal(queue.dequeue(), None)\n",
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"\n",
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" print('Test: Enqueue to an empty queue')\n",
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" queue.enqueue(1)\n",
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"\n",
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" print('Test: Dequeue a queue with one element')\n",
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" assert_equal(queue.dequeue(), 1)\n",
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"\n",
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" print('Test: Enqueue to a non-empty queue')\n",
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" queue.enqueue(2)\n",
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" queue.enqueue(3)\n",
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" queue.enqueue(4)\n",
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"\n",
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" print('Test: Dequeue a queue with more than one element')\n",
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" assert_equal(queue.dequeue(), 2)\n",
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" assert_equal(queue.dequeue(), 3)\n",
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" assert_equal(queue.dequeue(), 4)\n",
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" \n",
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" print('Success: test_end_to_end')\n",
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"\n",
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"def main():\n",
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" test = TestQueue()\n",
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" test.test_end_to_end()\n",
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" \n",
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"if __name__ == '__main__':\n",
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" main()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Solution Notebook\n",
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"\n",
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"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."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 2",
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"language": "python",
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"name": "python2"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 2
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython2",
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"version": "2.7.10"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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@@ -4,7 +4,14 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<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>"
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"<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>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Solution Notebook"
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]
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},
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{
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@@ -27,11 +34,13 @@
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"source": [
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"## Constraints\n",
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"\n",
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"*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
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"*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
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"\n",
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"* If there is one item in the list, do you expect the first and last pointers to both point to it?\n",
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" * Yes\n",
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"* If there are no items on the list, do you expect the first and last pointers to be NULL?\n",
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" * Yes\n",
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"* If you dequeue on an empty queue, does that return None?\n",
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" * Yes"
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]
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},
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@@ -48,7 +57,7 @@
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"\n",
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"### Dequeue\n",
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"\n",
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"* Dequeue an empty queue\n",
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"* Dequeue an empty queue -> None\n",
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"* Dequeue a queue with one element\n",
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"* Dequeue a queue with more than one element"
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]
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@@ -109,15 +118,14 @@
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],
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"source": [
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"%%writefile queue_list.py\n",
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"# Need to avoid naming this queue.py as it \n",
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"# will conflict with IPython Notebook\n",
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"\n",
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"class Node(object):\n",
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" \n",
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" def __init__(self, data):\n",
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" self.data = data\n",
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" self.next = None\n",
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"\n",
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"class Queue(object):\n",
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" \n",
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" def __init__(self):\n",
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" self.first = None\n",
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" self.last = None\n",
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@@ -164,8 +172,7 @@
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"metadata": {},
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"source": [
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"## Unit Test\n",
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"\n",
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"*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.*"
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"\n"
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]
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},
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{
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@@ -179,19 +186,17 @@
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Test: Dequeue an empty queue\n",
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"Test: Enqueue to an empty queue\n",
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"Test: Dequeue a queue with one element\n",
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"Test: Enqueue to a non-empty queue\n",
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"Test: Dequeue a queue with more than one element\n",
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"Success: test_end_to_end\n"
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"Overwriting test_queue_list.py\n"
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]
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}
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],
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"source": [
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"%%writefile test_queue_list.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"class Test(object):\n",
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"\n",
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"class TestQueue(object):\n",
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" \n",
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" # TODO: It would be better if we had unit tests for each\n",
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" # method in addition to the following end-to-end test\n",
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" def test_end_to_end(self):\n",
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@@ -217,9 +222,36 @@
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" \n",
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" print('Success: test_end_to_end')\n",
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"\n",
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"def main():\n",
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" test = TestQueue()\n",
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" test.test_end_to_end()\n",
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" \n",
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"if __name__ == '__main__':\n",
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" test = Test()\n",
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" test.test_end_to_end()"
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" main()"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Test: Dequeue an empty queue\n",
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"Test: Enqueue to an empty queue\n",
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"Test: Dequeue a queue with one element\n",
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"Test: Enqueue to a non-empty queue\n",
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"Test: Dequeue a queue with more than one element\n",
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"Success: test_end_to_end\n"
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]
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}
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],
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"source": [
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"%run -i test_queue_list.py"
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]
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},
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{
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36
stacks_queues/queue_list/test_queue_list.py
Normal file
36
stacks_queues/queue_list/test_queue_list.py
Normal file
@@ -0,0 +1,36 @@
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from nose.tools import assert_equal
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class TestQueue(object):
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|
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# TODO: It would be better if we had unit tests for each
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# method in addition to the following end-to-end test
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def test_end_to_end(self):
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print('Test: Dequeue an empty queue')
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queue = Queue()
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assert_equal(queue.dequeue(), None)
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print('Test: Enqueue to an empty queue')
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queue.enqueue(1)
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print('Test: Dequeue a queue with one element')
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assert_equal(queue.dequeue(), 1)
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print('Test: Enqueue to a non-empty queue')
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queue.enqueue(2)
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queue.enqueue(3)
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queue.enqueue(4)
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print('Test: Dequeue a queue with more than one element')
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assert_equal(queue.dequeue(), 2)
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assert_equal(queue.dequeue(), 3)
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assert_equal(queue.dequeue(), 4)
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print('Success: test_end_to_end')
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def main():
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test = TestQueue()
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test.test_end_to_end()
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if __name__ == '__main__':
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main()
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Reference in New Issue
Block a user