From 0f34948626065420b44b13d46f9171d3a2f2ef15 Mon Sep 17 00:00:00 2001 From: Donne Martin Date: Fri, 3 Jul 2015 19:56:11 -0400 Subject: [PATCH] Added hash map challenge. --- .../hash_map/hash_map_challenge.ipynb | 217 ++++++++++++++++++ .../hash_map/hash_map_solution.ipynb | 66 ++++-- arrays_strings/hash_map/test_hash_map.py | 45 ++++ 3 files changed, 308 insertions(+), 20 deletions(-) create mode 100644 arrays_strings/hash_map/hash_map_challenge.ipynb create mode 100644 arrays_strings/hash_map/test_hash_map.py diff --git a/arrays_strings/hash_map/hash_map_challenge.ipynb b/arrays_strings/hash_map/hash_map_challenge.ipynb new file mode 100644 index 0000000..a8801d1 --- /dev/null +++ b/arrays_strings/hash_map/hash_map_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 hash table with set, get, and remove methods.\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", + "* For simplicity, are the keys integers only?\n", + " * Yes\n", + "* For collision resolution, can we use linked lists?\n", + " * Yes\n", + "* Do we have to worry about load factors?\n", + " * No" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* get on an empty hash table index\n", + "* set on an empty hash table index\n", + "* set on a non empty hash table index\n", + "* set on a key that already exists\n", + "* remove on a key with an entry\n", + "* remove on a key without an entry" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/arrays_strings/hash_map/hash_map_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 Item(object):\n", + " \n", + " def __init__(self, key, value):\n", + " # TODO: Implement me\n", + " pass\n", + "\n", + "class HashTable(object):\n", + " \n", + " def __init__(self, size):\n", + " # TODO: Implement me\n", + " pass\n", + "\n", + " def hash_function(self, key):\n", + " # TODO: Implement me\n", + " pass\n", + "\n", + " def set(self, key, value):\n", + " # TODO: Implement me\n", + " pass\n", + "\n", + " def get(self, key):\n", + " # TODO: Implement me\n", + " pass\n", + "\n", + " def remove(self, key):\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_hash_map.py\n", + "from nose.tools import assert_equal\n", + "\n", + "\n", + "class TestHashMap(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", + " hash_table = HashTable(10)\n", + " \n", + " print(\"Test: get on an empty hash table index\")\n", + " assert_equal(hash_table.get(0), None)\n", + " \n", + " print(\"Test: set on an empty hash table index\")\n", + " hash_table.set(0, 'foo')\n", + " assert_equal(hash_table.get(0), 'foo')\n", + " hash_table.set(1, 'bar')\n", + " assert_equal(hash_table.get(1), 'bar')\n", + " \n", + " print(\"Test: set on a non empty hash table index\")\n", + " hash_table.set(10, 'foo2')\n", + " assert_equal(hash_table.get(0), 'foo')\n", + " assert_equal(hash_table.get(10), 'foo2')\n", + " \n", + " print(\"Test: set on a key that already exists\")\n", + " hash_table.set(10, 'foo3')\n", + " assert_equal(hash_table.get(0), 'foo')\n", + " assert_equal(hash_table.get(10), 'foo3')\n", + " \n", + " print(\"Test: remove on a key that already exists\")\n", + " hash_table.remove(10)\n", + " assert_equal(hash_table.get(0), 'foo')\n", + " assert_equal(hash_table.get(10), None)\n", + " \n", + " print(\"Test: remove on a key that doesn't exist\")\n", + " hash_table.remove(-1)\n", + " \n", + " print('Success: test_end_to_end')\n", + "\n", + "def main():\n", + " test = TestHashMap()\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/arrays_strings/hash_map/hash_map_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/arrays_strings/hash_map/hash_map_solution.ipynb b/arrays_strings/hash_map/hash_map_solution.ipynb index 68b6b39..908957e 100644 --- a/arrays_strings/hash_map/hash_map_solution.ipynb +++ b/arrays_strings/hash_map/hash_map_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" ] }, { @@ -17,7 +24,6 @@ "* [Test Cases](#Test-Cases)\n", "* [Algorithm](#Algorithm)\n", "* [Code](#Code)\n", - "* [Pythonic-Code](#Pythonic-Code)\n", "* [Unit Test](#Unit-Test)" ] }, @@ -27,7 +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", "* For simplicity, are the keys integers only?\n", " * Yes\n", @@ -111,11 +117,13 @@ "outputs": [], "source": [ "class Item(object):\n", + " \n", " def __init__(self, key, value):\n", " self.key = key\n", " self.value = value\n", "\n", "class HashTable(object):\n", + " \n", " def __init__(self, size):\n", " self.size = size\n", " self.table = [[] for _ in xrange(self.size)]\n", @@ -152,13 +160,6 @@ "## 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": 2, @@ -170,20 +171,17 @@ "name": "stdout", "output_type": "stream", "text": [ - "Test: get on an empty hash table index\n", - "Test: set on an empty hash table index\n", - "Test: set on a non empty hash table index\n", - "Test: set on a key that already exists\n", - "Test: remove on a key that already exists\n", - "Test: remove on a key that doesn't exist\n", - "Success: test_end_to_end\n" + "Overwriting test_hash_map.py\n" ] } ], "source": [ + "%%writefile test_hash_map.py\n", "from nose.tools import assert_equal\n", "\n", - "class Test(object):\n", + "\n", + "class TestHashMap(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", @@ -218,9 +216,37 @@ " \n", " print('Success: test_end_to_end')\n", "\n", + "def main():\n", + " test = TestHashMap()\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": 3, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Test: get on an empty hash table index\n", + "Test: set on an empty hash table index\n", + "Test: set on a non empty hash table index\n", + "Test: set on a key that already exists\n", + "Test: remove on a key that already exists\n", + "Test: remove on a key that doesn't exist\n", + "Success: test_end_to_end\n" + ] + } + ], + "source": [ + "run -i test_hash_map.py" ] } ], diff --git a/arrays_strings/hash_map/test_hash_map.py b/arrays_strings/hash_map/test_hash_map.py new file mode 100644 index 0000000..2ed8a77 --- /dev/null +++ b/arrays_strings/hash_map/test_hash_map.py @@ -0,0 +1,45 @@ +from nose.tools import assert_equal + + +class TestHashMap(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): + hash_table = HashTable(10) + + print("Test: get on an empty hash table index") + assert_equal(hash_table.get(0), None) + + print("Test: set on an empty hash table index") + hash_table.set(0, 'foo') + assert_equal(hash_table.get(0), 'foo') + hash_table.set(1, 'bar') + assert_equal(hash_table.get(1), 'bar') + + print("Test: set on a non empty hash table index") + hash_table.set(10, 'foo2') + assert_equal(hash_table.get(0), 'foo') + assert_equal(hash_table.get(10), 'foo2') + + print("Test: set on a key that already exists") + hash_table.set(10, 'foo3') + assert_equal(hash_table.get(0), 'foo') + assert_equal(hash_table.get(10), 'foo3') + + print("Test: remove on a key that already exists") + hash_table.remove(10) + assert_equal(hash_table.get(0), 'foo') + assert_equal(hash_table.get(10), None) + + print("Test: remove on a key that doesn't exist") + hash_table.remove(-1) + + print('Success: test_end_to_end') + +def main(): + test = TestHashMap() + test.test_end_to_end() + +if __name__ == '__main__': + main() \ No newline at end of file