mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Added hash map challenge.
This commit is contained in:
Donne Martin
parent
8b9a1473ea
commit
0f34948626
217
arrays_strings/hash_map/hash_map_challenge.ipynb
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217
arrays_strings/hash_map/hash_map_challenge.ipynb
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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 hash table with set, get, and remove methods.\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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"* [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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"* For simplicity, are the keys integers only?\n",
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" * Yes\n",
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"* For collision resolution, can we use linked lists?\n",
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" * Yes\n",
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"* Do we have to worry about load factors?\n",
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" * No"
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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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"* get on an empty hash table index\n",
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"* set on an empty hash table index\n",
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"* set on a non empty hash table index\n",
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"* set on a key that already exists\n",
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"* remove on a key with an entry\n",
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"* remove on a key without an entry"
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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/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."
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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 Item(object):\n",
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" \n",
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" def __init__(self, key, value):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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"class HashTable(object):\n",
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" \n",
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" def __init__(self, size):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def hash_function(self, key):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def set(self, key, value):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def get(self, key):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def remove(self, key):\n",
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" # TODO: Implement me\n",
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" pass"
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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"
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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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"\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_hash_map.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 TestHashMap(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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" hash_table = HashTable(10)\n",
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" \n",
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" print(\"Test: get on an empty hash table index\")\n",
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" assert_equal(hash_table.get(0), None)\n",
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" \n",
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" print(\"Test: set on an empty hash table index\")\n",
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" hash_table.set(0, 'foo')\n",
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" assert_equal(hash_table.get(0), 'foo')\n",
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" hash_table.set(1, 'bar')\n",
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" assert_equal(hash_table.get(1), 'bar')\n",
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" \n",
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" print(\"Test: set on a non empty hash table index\")\n",
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" hash_table.set(10, 'foo2')\n",
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" assert_equal(hash_table.get(0), 'foo')\n",
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" assert_equal(hash_table.get(10), 'foo2')\n",
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" \n",
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" print(\"Test: set on a key that already exists\")\n",
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" hash_table.set(10, 'foo3')\n",
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" assert_equal(hash_table.get(0), 'foo')\n",
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" assert_equal(hash_table.get(10), 'foo3')\n",
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" \n",
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" print(\"Test: remove on a key that already exists\")\n",
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" hash_table.remove(10)\n",
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" assert_equal(hash_table.get(0), 'foo')\n",
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" assert_equal(hash_table.get(10), None)\n",
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" \n",
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" print(\"Test: remove on a key that doesn't exist\")\n",
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" hash_table.remove(-1)\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 = TestHashMap()\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/arrays_strings/hash_map/hash_map_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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@ -17,7 +24,6 @@
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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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"* [Pythonic-Code](#Pythonic-Code)\n",
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"* [Unit Test](#Unit-Test)"
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]
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},
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@ -27,7 +33,7 @@
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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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"* For simplicity, are the keys integers only?\n",
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" * Yes\n",
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@ -111,11 +117,13 @@
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"outputs": [],
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"source": [
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"class Item(object):\n",
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" \n",
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" def __init__(self, key, value):\n",
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" self.key = key\n",
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" self.value = value\n",
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"\n",
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"class HashTable(object):\n",
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" \n",
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" def __init__(self, size):\n",
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" self.size = size\n",
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" self.table = [[] for _ in xrange(self.size)]\n",
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@ -152,13 +160,6 @@
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"## Unit Test"
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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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"*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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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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@ -170,20 +171,17 @@
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Test: get on an empty hash table index\n",
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"Test: set on an empty hash table index\n",
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"Test: set on a non empty hash table index\n",
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"Test: set on a key that already exists\n",
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"Test: remove on a key that already exists\n",
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"Test: remove on a key that doesn't exist\n",
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"Success: test_end_to_end\n"
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"Overwriting test_hash_map.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_hash_map.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 TestHashMap(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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@ -218,9 +216,37 @@
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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 = TestHashMap()\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": 3,
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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: get on an empty hash table index\n",
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"Test: set on an empty hash table index\n",
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"Test: set on a non empty hash table index\n",
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"Test: set on a key that already exists\n",
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"Test: remove on a key that already exists\n",
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"Test: remove on a key that doesn't exist\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_hash_map.py"
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]
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}
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],
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45
arrays_strings/hash_map/test_hash_map.py
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45
arrays_strings/hash_map/test_hash_map.py
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@ -0,0 +1,45 @@
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from nose.tools import assert_equal
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class TestHashMap(object):
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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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hash_table = HashTable(10)
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print("Test: get on an empty hash table index")
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assert_equal(hash_table.get(0), None)
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print("Test: set on an empty hash table index")
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hash_table.set(0, 'foo')
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assert_equal(hash_table.get(0), 'foo')
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hash_table.set(1, 'bar')
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assert_equal(hash_table.get(1), 'bar')
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print("Test: set on a non empty hash table index")
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hash_table.set(10, 'foo2')
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assert_equal(hash_table.get(0), 'foo')
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assert_equal(hash_table.get(10), 'foo2')
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print("Test: set on a key that already exists")
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hash_table.set(10, 'foo3')
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assert_equal(hash_table.get(0), 'foo')
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assert_equal(hash_table.get(10), 'foo3')
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print("Test: remove on a key that already exists")
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hash_table.remove(10)
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assert_equal(hash_table.get(0), 'foo')
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assert_equal(hash_table.get(10), None)
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print("Test: remove on a key that doesn't exist")
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hash_table.remove(-1)
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print('Success: test_end_to_end')
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def main():
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test = TestHashMap()
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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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Block a user