mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Add radix sort challenge
This commit is contained in:
Donne Martin
parent
256755a962
commit
c915ea69f5
0
sorting_searching/radix_sort/__init__.py
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0
sorting_searching/radix_sort/__init__.py
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170
sorting_searching/radix_sort/radix_sort_challenge.ipynb
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170
sorting_searching/radix_sort/radix_sort_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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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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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 radix sort.\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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"* Is the input a list?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * Check for None in place of an array\n",
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" * Assume array elements are ints\n",
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"* Do we know the max digits to handle?\n",
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" * No\n",
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"* Are the digits base 10?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\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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"* None -> Exception\n",
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"* [] -> []\n",
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"* [128, 256, 164, 8, 2, 148, 212, 242, 244] -> [2, 8, 128, 148, 164, 212, 242, 244, 256]"
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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](). 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 RadixSort(object):\n",
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"\n",
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" def sort(self, array, base=10):\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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"**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_radix_sort.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestRadixSort(object):\n",
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"\n",
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" def test_sort(self):\n",
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" radix_sort = RadixSort()\n",
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" assert_raises(TypeError, radix_sort.sort, None)\n",
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" assert_equal(radix_sort.sort([]), [])\n",
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" array = [128, 256, 164, 8, 2, 148, 212, 242, 244]\n",
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" expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]\n",
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" assert_equal(radix_sort.sort(array), expected)\n",
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" print('Success: test_sort')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestRadixSort()\n",
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" test.test_sort()\n",
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"\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]() 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 3",
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"language": "python",
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"name": "python3"
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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": 3
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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": "ipython3",
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"version": "3.5.0"
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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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232
sorting_searching/radix_sort/radix_sort_solution.ipynb
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232
sorting_searching/radix_sort/radix_sort_solution.ipynb
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@ -0,0 +1,232 @@
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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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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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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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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Implement radix sort.\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)"
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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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"* Is the input a list?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * Check for None in place of an array\n",
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" * Assume array elements are ints\n",
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"* Do we know the max digits to handle?\n",
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" * No\n",
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"* Are the digits base 10?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\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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"* None -> Exception\n",
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"* [] -> []\n",
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"* [128, 256, 164, 8, 2, 148, 212, 242, 244] -> [2, 8, 128, 148, 164, 212, 242, 244, 256]"
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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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"Sample input: [1, 220, 122, 112]\n",
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"\n",
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"* We'll evaluate each digit starting with the ones position\n",
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" * [**1**, 22**0**, 12**2**, 11**2**]\n",
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" * Bucket 0: 220\n",
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" * Bucket 1: 1\n",
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" * Bucket 2: 122, 112\n",
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" * Result: [220, 1, 122, 112]\n",
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" * [2**2**0, 1, 1**2**2, 1**1**2]\n",
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" * Bucket 0: 1\n",
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" * Bucket 1: 112\n",
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" * Bucket 2: 220, 122\n",
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" * Result: [1, 112, 220, 122]\n",
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" * [1, **1**12, **2**20, **1**22]\n",
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" * Bucket 0: 1\n",
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" * Bucket 1: 112, 122\n",
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" * Bucket 2: 220\n",
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" * Result: [1, 112, 122, 220]\n",
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"\n",
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"Bucketing example: 123\n",
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"\n",
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"* Ones\n",
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" * 12**3** // 10^0 = 123\n",
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" * 123 % 10 = 3\n",
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"* Tens\n",
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" * 1**2**3 // 10^1 = 12\n",
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" * 12 % 10 = 2\n",
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"* Hundreds\n",
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" * **1**23 // 10^2 = 1\n",
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" * 1 % 10 = 1\n",
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"\n",
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"Complexity:\n",
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"* Time: O(k*n), where n is the number of items and k is the number of digits in the largest item\n",
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"* Space: O(k+n)\n",
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"\n",
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"Misc:\n",
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"* Not in-place\n",
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"* Most implementations are stable\n",
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"\n",
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"If k (the number of digits) is less than log(n), radix sort can be faster than algorithms such as quicksort."
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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": 1,
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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 RadixSort(object):\n",
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"\n",
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" def sort(self, array, base=10):\n",
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" if array is None:\n",
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" raise TypeError('array cannot be None')\n",
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" if not array:\n",
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" return []\n",
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" max_element = max(array)\n",
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" max_digits = len(str(abs(max_element)))\n",
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" curr_array = array\n",
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" for digit in range(max_digits):\n",
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" buckets = [[] for _ in range(base)]\n",
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" for item in curr_array:\n",
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" buckets[(item//(base**digit))%base].append(item)\n",
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" curr_array = []\n",
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" for bucket in buckets:\n",
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" curr_array.extend(bucket)\n",
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" return curr_array"
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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": "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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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting test_radix_sort.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_radix_sort.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestRadixSort(object):\n",
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"\n",
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" def test_sort(self):\n",
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" radix_sort = RadixSort()\n",
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" assert_raises(TypeError, radix_sort.sort, None)\n",
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" assert_equal(radix_sort.sort([]), [])\n",
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" array = [128, 256, 164, 8, 2, 148, 212, 242, 244]\n",
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" expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]\n",
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" assert_equal(radix_sort.sort(array), expected)\n",
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" print('Success: test_sort')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestRadixSort()\n",
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" test.test_sort()\n",
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"\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": "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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"Success: test_sort\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_radix_sort.py"
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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 3",
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"language": "python",
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"name": "python3"
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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": 3
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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": "ipython3",
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"version": "3.5.0"
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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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22
sorting_searching/radix_sort/test_radix_sort.py
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sorting_searching/radix_sort/test_radix_sort.py
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@ -0,0 +1,22 @@
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from nose.tools import assert_equal, assert_raises
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class TestRadixSort(object):
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def test_sort(self):
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radix_sort = RadixSort()
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assert_raises(TypeError, radix_sort.sort, None)
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assert_equal(radix_sort.sort([]), [])
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array = [128, 256, 164, 8, 2, 148, 212, 242, 244]
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expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]
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assert_equal(radix_sort.sort(array), expected)
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print('Success: test_sort')
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def main():
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test = TestRadixSort()
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test.test_sort()
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if __name__ == '__main__':
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main()
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