mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Added remove duplicates challenge.
This commit is contained in:
Donne Martin
parent
c16f25e5f3
commit
d253a4929a
0
linked_lists/remove_duplicates/__init__.py
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0
linked_lists/remove_duplicates/__init__.py
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198
linked_lists/remove_duplicates/remove_duplicates_challenge.ipynb
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198
linked_lists/remove_duplicates/remove_duplicates_challenge.ipynb
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@ -0,0 +1,198 @@
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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: Remove duplicates from 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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"* [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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"* Is this a singly or doubly linked list?\n",
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" * Singly\n",
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"* Can you insert NULL values in the list?\n",
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" * No\n",
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"* Can you use additional data structures?\n",
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" * Implement both solutions\n",
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"* Can we assume we already have a linked list class that can be used for this problem?\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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"* Empty linked list -> []\n",
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"* One element linked list -> [element]\n",
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"* General case with no duplicates\n",
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"* General case with duplicates"
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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/linked_lists/remove_duplicates/remove_duplicates_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": true
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},
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"outputs": [],
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"source": [
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"%run ../linked_list/linked_list.py\n",
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"%load ../linked_list/linked_list.py"
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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 MyLinkedList(LinkedList):\n",
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" \n",
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" def remove_dupes(self):\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_remove_duplicates.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 TestRemoveDupes(object):\n",
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" \n",
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" def test_remove_dupes(self, linked_list):\n",
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" print('Test: Empty list')\n",
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" linked_list.remove_dupes()\n",
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" assert_equal(linked_list.get_all_data(), [])\n",
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"\n",
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" print('Test: One element list')\n",
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" linked_list.insert_to_front(2)\n",
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" linked_list.remove_dupes()\n",
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" assert_equal(linked_list.get_all_data(), [2])\n",
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"\n",
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" print('Test: General case, duplicates')\n",
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" linked_list.insert_to_front(1)\n",
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" linked_list.insert_to_front(3)\n",
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" linked_list.insert_to_front(1)\n",
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" linked_list.insert_to_front(1)\n",
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" linked_list.remove_dupes()\n",
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" assert_equal(linked_list.get_all_data(), [1, 3, 2])\n",
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"\n",
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" print('Test: General case, no duplicates')\n",
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" linked_list.remove_dupes()\n",
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" assert_equal(linked_list.get_all_data(), [1, 3, 2])\n",
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" \n",
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" print('Success: test_remove_dupes\\n')\n",
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"\n",
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"def main():\n",
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" test = TestRemoveDupes()\n",
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" linked_list = MyLinkedList(None)\n",
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" test.test_remove_dupes(linked_list)\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/linked_lists/remove_duplicates/remove_duplicates_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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@ -16,9 +23,8 @@
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm: Hash Map Lookup](#Algorithm:-Hash-Map-Lookup)\n",
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"* [Code: Hash Map Lookup](#Code:-Hash-Map-Lookup)\n",
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"* [Algorithm: In-Place](#Algorithm:-In-Place)\n",
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"* [Code: In-Place](#Code:-In-Place)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)"
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]
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},
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@ -28,7 +34,7 @@
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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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"* Is this a singly or doubly linked list?\n",
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" * Singly\n",
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@ -46,11 +52,10 @@
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"source": [
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"## Test Cases\n",
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"\n",
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"* Empty linked list\n",
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"* One element linked list\n",
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"* Multiple elements\n",
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"* No duplicates\n",
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"* One or more duplicates"
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"* Empty linked list -> []\n",
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"* One element linked list -> [element]\n",
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"* General case with no duplicates\n",
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"* General case with duplicates"
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]
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},
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{
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@ -73,46 +78,6 @@
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"* Deletion requires two pointers, one to the previous node and one to the current node"
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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: Hash Map Lookup"
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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": 1,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run linked_list.py"
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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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"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 MyLinkedList(LinkedList):\n",
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" def remove_dupes(self):\n",
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" seen_data = set()\n",
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" curr = self.head\n",
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" prev = None\n",
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" while curr is not None:\n",
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" if curr.data in seen_data:\n",
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" prev.next = curr.next\n",
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" else:\n",
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" seen_data.add(curr.data)\n",
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" prev = curr\n",
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" curr = curr.next"
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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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@ -139,19 +104,43 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code: In-Place"
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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": 3,
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"execution_count": 1,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run ../linked_list/linked_list.py"
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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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"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 MyLinkedListAlt(LinkedList):\n",
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"class MyLinkedList(LinkedList):\n",
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" \n",
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" def remove_dupes(self):\n",
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" seen_data = set()\n",
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" curr = self.head\n",
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" prev = None\n",
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" while curr is not None:\n",
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" if curr.data in seen_data:\n",
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" prev.next = curr.next\n",
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" else:\n",
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" seen_data.add(curr.data)\n",
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" prev = curr\n",
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" curr = curr.next\n",
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" \n",
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" def remove_dupes_in_place(self):\n",
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" curr = self.head\n",
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" while curr is not None:\n",
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" runner = curr\n",
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@ -170,16 +159,9 @@
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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": 4,
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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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@ -188,25 +170,17 @@
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Test: Empty list\n",
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"Test: One element list\n",
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"Test: General case, duplicates\n",
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"Test: General case, no duplicates\n",
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"Success: test_remove_dupes\n",
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"\n",
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"Test: Empty list\n",
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"Test: One element list\n",
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"Test: General case, duplicates\n",
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"Test: General case, no duplicates\n",
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"Success: test_remove_dupes\n",
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"\n"
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"Overwriting test_remove_duplicates.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_remove_duplicates.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 TestRemoveDupes(object):\n",
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" \n",
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" def test_remove_dupes(self, linked_list):\n",
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" print('Test: Empty list')\n",
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" linked_list.remove_dupes()\n",
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@ -231,12 +205,37 @@
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" \n",
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" print('Success: test_remove_dupes\\n')\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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"def main():\n",
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" test = TestRemoveDupes()\n",
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" linked_list = MyLinkedList(None)\n",
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" test.test_remove_dupes(linked_list)\n",
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" linked_list_alt = MyLinkedListAlt(None)\n",
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" test.test_remove_dupes(linked_list_alt)"
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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": "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: Empty list\n",
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"Test: One element list\n",
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"Test: General case, duplicates\n",
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"Test: General case, no duplicates\n",
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"Success: test_remove_dupes\n",
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"\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_remove_duplicates.py"
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]
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}
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],
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36
linked_lists/remove_duplicates/test_remove_duplicates.py
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36
linked_lists/remove_duplicates/test_remove_duplicates.py
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from nose.tools import assert_equal
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class TestRemoveDupes(object):
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def test_remove_dupes(self, linked_list):
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print('Test: Empty list')
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linked_list.remove_dupes()
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assert_equal(linked_list.get_all_data(), [])
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print('Test: One element list')
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linked_list.insert_to_front(2)
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linked_list.remove_dupes()
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assert_equal(linked_list.get_all_data(), [2])
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print('Test: General case, duplicates')
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linked_list.insert_to_front(1)
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linked_list.insert_to_front(3)
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linked_list.insert_to_front(1)
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linked_list.insert_to_front(1)
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linked_list.remove_dupes()
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assert_equal(linked_list.get_all_data(), [1, 3, 2])
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print('Test: General case, no duplicates')
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linked_list.remove_dupes()
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assert_equal(linked_list.get_all_data(), [1, 3, 2])
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print('Success: test_remove_dupes\n')
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def main():
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test = TestRemoveDupes()
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linked_list = MyLinkedList(None)
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test.test_remove_dupes(linked_list)
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if __name__ == '__main__':
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main()
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Block a user