diff --git a/sorting_searching/radix_sort/__init__.py b/sorting_searching/radix_sort/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/sorting_searching/radix_sort/radix_sort_challenge.ipynb b/sorting_searching/radix_sort/radix_sort_challenge.ipynb new file mode 100644 index 0000000..be3b216 --- /dev/null +++ b/sorting_searching/radix_sort/radix_sort_challenge.ipynb @@ -0,0 +1,170 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "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)." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Challenge Notebook" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Problem: Implement radix sort.\n", + "\n", + "* [Constraints](#Constraints)\n", + "* [Test Cases](#Test-Cases)\n", + "* [Algorithm](#Algorithm)\n", + "* [Code](#Code)\n", + "* [Unit Test](#Unit-Test)\n", + "* [Solution Notebook](#Solution-Notebook)" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Constraints\n", + "\n", + "* Is the input a list?\n", + " * Yes\n", + "* Can we assume the inputs are valid?\n", + " * Check for None in place of an array\n", + " * Assume array elements are ints\n", + "* Do we know the max digits to handle?\n", + " * No\n", + "* Are the digits base 10?\n", + " * Yes\n", + "* Can we assume this fits memory?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* None -> Exception\n", + "* [] -> []\n", + "* [128, 256, 164, 8, 2, 148, 212, 242, 244] -> [2, 8, 128, 148, 164, 212, 242, 244, 256]" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "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." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Code" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "class RadixSort(object):\n", + "\n", + " def sort(self, array, base=10):\n", + " # TODO: Implement me\n", + " pass" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Unit Test" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "**The following unit test is expected to fail until you solve the challenge.**" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "# %load test_radix_sort.py\n", + "from nose.tools import assert_equal, assert_raises\n", + "\n", + "\n", + "class TestRadixSort(object):\n", + "\n", + " def test_sort(self):\n", + " radix_sort = RadixSort()\n", + " assert_raises(TypeError, radix_sort.sort, None)\n", + " assert_equal(radix_sort.sort([]), [])\n", + " array = [128, 256, 164, 8, 2, 148, 212, 242, 244]\n", + " expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]\n", + " assert_equal(radix_sort.sort(array), expected)\n", + " print('Success: test_sort')\n", + "\n", + "\n", + "def main():\n", + " test = TestRadixSort()\n", + " test.test_sort()\n", + "\n", + "\n", + "if __name__ == '__main__':\n", + " main()" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Solution Notebook\n", + "\n", + "Review the [Solution Notebook]() for a discussion on algorithms and code solutions." + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 3", + "language": "python", + "name": "python3" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 3 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython3", + "version": "3.5.0" + } + }, + "nbformat": 4, + "nbformat_minor": 0 +} diff --git a/sorting_searching/radix_sort/radix_sort_solution.ipynb b/sorting_searching/radix_sort/radix_sort_solution.ipynb new file mode 100644 index 0000000..96d8827 --- /dev/null +++ b/sorting_searching/radix_sort/radix_sort_solution.ipynb @@ -0,0 +1,232 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "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)." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Solution Notebook" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Problem: Implement radix sort.\n", + "\n", + "* [Constraints](#Constraints)\n", + "* [Test Cases](#Test-Cases)\n", + "* [Algorithm](#Algorithm)\n", + "* [Code](#Code)\n", + "* [Unit Test](#Unit-Test)" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Constraints\n", + "\n", + "* Is the input a list?\n", + " * Yes\n", + "* Can we assume the inputs are valid?\n", + " * Check for None in place of an array\n", + " * Assume array elements are ints\n", + "* Do we know the max digits to handle?\n", + " * No\n", + "* Are the digits base 10?\n", + " * Yes\n", + "* Can we assume this fits memory?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* None -> Exception\n", + "* [] -> []\n", + "* [128, 256, 164, 8, 2, 148, 212, 242, 244] -> [2, 8, 128, 148, 164, 212, 242, 244, 256]" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "Sample input: [1, 220, 122, 112]\n", + "\n", + "* We'll evaluate each digit starting with the ones position\n", + " * [**1**, 22**0**, 12**2**, 11**2**]\n", + " * Bucket 0: 220\n", + " * Bucket 1: 1\n", + " * Bucket 2: 122, 112\n", + " * Result: [220, 1, 122, 112]\n", + " * [2**2**0, 1, 1**2**2, 1**1**2]\n", + " * Bucket 0: 1\n", + " * Bucket 1: 112\n", + " * Bucket 2: 220, 122\n", + " * Result: [1, 112, 220, 122]\n", + " * [1, **1**12, **2**20, **1**22]\n", + " * Bucket 0: 1\n", + " * Bucket 1: 112, 122\n", + " * Bucket 2: 220\n", + " * Result: [1, 112, 122, 220]\n", + "\n", + "Bucketing example: 123\n", + "\n", + "* Ones\n", + " * 12**3** // 10^0 = 123\n", + " * 123 % 10 = 3\n", + "* Tens\n", + " * 1**2**3 // 10^1 = 12\n", + " * 12 % 10 = 2\n", + "* Hundreds\n", + " * **1**23 // 10^2 = 1\n", + " * 1 % 10 = 1\n", + "\n", + "Complexity:\n", + "* Time: O(k*n), where n is the number of items and k is the number of digits in the largest item\n", + "* Space: O(k+n)\n", + "\n", + "Misc:\n", + "* Not in-place\n", + "* Most implementations are stable\n", + "\n", + "If k (the number of digits) is less than log(n), radix sort can be faster than algorithms such as quicksort." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Code" + ] + }, + { + "cell_type": "code", + "execution_count": 1, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "class RadixSort(object):\n", + "\n", + " def sort(self, array, base=10):\n", + " if array is None:\n", + " raise TypeError('array cannot be None')\n", + " if not array:\n", + " return []\n", + " max_element = max(array)\n", + " max_digits = len(str(abs(max_element)))\n", + " curr_array = array\n", + " for digit in range(max_digits):\n", + " buckets = [[] for _ in range(base)]\n", + " for item in curr_array:\n", + " buckets[(item//(base**digit))%base].append(item)\n", + " curr_array = []\n", + " for bucket in buckets:\n", + " curr_array.extend(bucket)\n", + " return curr_array" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Unit Test" + ] + }, + { + "cell_type": "code", + "execution_count": 2, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Overwriting test_radix_sort.py\n" + ] + } + ], + "source": [ + "%%writefile test_radix_sort.py\n", + "from nose.tools import assert_equal, assert_raises\n", + "\n", + "\n", + "class TestRadixSort(object):\n", + "\n", + " def test_sort(self):\n", + " radix_sort = RadixSort()\n", + " assert_raises(TypeError, radix_sort.sort, None)\n", + " assert_equal(radix_sort.sort([]), [])\n", + " array = [128, 256, 164, 8, 2, 148, 212, 242, 244]\n", + " expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]\n", + " assert_equal(radix_sort.sort(array), expected)\n", + " print('Success: test_sort')\n", + "\n", + "\n", + "def main():\n", + " test = TestRadixSort()\n", + " test.test_sort()\n", + "\n", + "\n", + "if __name__ == '__main__':\n", + " main()" + ] + }, + { + "cell_type": "code", + "execution_count": 3, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Success: test_sort\n" + ] + } + ], + "source": [ + "%run -i test_radix_sort.py" + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 3", + "language": "python", + "name": "python3" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 3 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython3", + "version": "3.5.0" + } + }, + "nbformat": 4, + "nbformat_minor": 0 +} diff --git a/sorting_searching/radix_sort/test_radix_sort.py b/sorting_searching/radix_sort/test_radix_sort.py new file mode 100644 index 0000000..0dbbed2 --- /dev/null +++ b/sorting_searching/radix_sort/test_radix_sort.py @@ -0,0 +1,22 @@ +from nose.tools import assert_equal, assert_raises + + +class TestRadixSort(object): + + def test_sort(self): + radix_sort = RadixSort() + assert_raises(TypeError, radix_sort.sort, None) + assert_equal(radix_sort.sort([]), []) + array = [128, 256, 164, 8, 2, 148, 212, 242, 244] + expected = [2, 8, 128, 148, 164, 212, 242, 244, 256] + assert_equal(radix_sort.sort(array), expected) + print('Success: test_sort') + + +def main(): + test = TestRadixSort() + test.test_sort() + + +if __name__ == '__main__': + main() \ No newline at end of file