From fb7de503af64051ed9c4b7afc0bcc267a1e20566 Mon Sep 17 00:00:00 2001 From: Donne Martin Date: Fri, 3 Jul 2015 19:56:38 -0400 Subject: [PATCH] Added permutation challenge. --- .../permutation/permutation_challenge.ipynb | 171 ++++++++++++++++++ .../permutation/permutation_solution.ipynb | 75 +++++--- .../permutation/test_permutation_solution.py | 24 +++ 3 files changed, 248 insertions(+), 22 deletions(-) create mode 100644 arrays_strings/permutation/permutation_challenge.ipynb create mode 100644 arrays_strings/permutation/test_permutation_solution.py diff --git a/arrays_strings/permutation/permutation_challenge.ipynb b/arrays_strings/permutation/permutation_challenge.ipynb new file mode 100644 index 0000000..9b6d371 --- /dev/null +++ b/arrays_strings/permutation/permutation_challenge.ipynb @@ -0,0 +1,171 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges)." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Challenge Notebook" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Problem: Determine if a string is a permutation of another string\n", + "\n", + "* [Constraints](#Constraints)\n", + "* [Test Cases](#Test-Cases)\n", + "* [Algorithm](#Algorithm)\n", + "* [Code](#Code)\n", + "* [Unit Test](#Unit-Test)\n", + "* [Solution Notebook](#Solution-Notebook)" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Constraints\n", + "\n", + "*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n", + "\n", + "* Can we assume the string is ASCII?\n", + " * Yes\n", + " * Note: Unicode strings could require special handling depending on your language\n", + "* Is whitespace important?\n", + " * Yes\n", + "* Is this case sensitive? 'Nib', 'bin' is not a match?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* One or more empty strings -> False\n", + "* 'Nib', 'bin' -> False\n", + "* 'act', 'cat' -> True\n", + "* 'a ct', 'ca t' -> True" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/arrays_strings/permutation/permutation_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Code" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "def permutations(str1, str2):\n", + " # TODO: Implement me\n", + " pass" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Unit Test" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "\n", + "\n", + "**The following unit test is expected to fail until you solve the challenge.**" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "# %load test_permutation_solution.py\n", + "from nose.tools import assert_equal\n", + "\n", + "\n", + "class TestPermutation(object):\n", + " \n", + " def test_permutation(self, func):\n", + " assert_equal(func('', 'foo'), False)\n", + " assert_equal(func('Nib', 'bin'), False)\n", + " assert_equal(func('act', 'cat'), True)\n", + " assert_equal(func('a ct', 'ca t'), True)\n", + " print('Success: test_permutation')\n", + "\n", + "def main():\n", + " test = TestPermutation()\n", + " test.test_permutation(permutations)\n", + " try:\n", + " test.test_permutation(permutations_alt)\n", + " except NameError:\n", + " # Alternate solutions are only defined\n", + " # in the solutions file\n", + " pass\n", + " \n", + "if __name__ == '__main__':\n", + " main()" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Solution Notebook\n", + "\n", + "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/arrays_strings/permutation/permutation_solution.ipynb) for a discussion on algorithms and code solutions." + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 2", + "language": "python", + "name": "python2" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 2 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython2", + "version": "2.7.10" + } + }, + "nbformat": 4, + "nbformat_minor": 0 +} diff --git a/arrays_strings/permutation/permutation_solution.ipynb b/arrays_strings/permutation/permutation_solution.ipynb index 57a25f3..e60608b 100644 --- a/arrays_strings/permutation/permutation_solution.ipynb +++ b/arrays_strings/permutation/permutation_solution.ipynb @@ -4,7 +4,14 @@ "cell_type": "markdown", "metadata": {}, "source": [ - "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes)." + "This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges)." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Solution Notebook" ] }, { @@ -28,9 +35,9 @@ "source": [ "## Constraints\n", "\n", - "*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n", + "*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n", "\n", - "* Can I assume the string is ASCII?\n", + "* Can we assume the string is ASCII?\n", " * Yes\n", " * Note: Unicode strings could require special handling depending on your language\n", "* Is whitespace important?\n", @@ -110,7 +117,7 @@ "Notes:\n", "* Since the characters are in ASCII, we could potentially use an array of size 128 (or 256 for extended ASCII), where each array index is equivalent to an ASCII value\n", "* Instead of using two hash maps, you could use one hash map and increment character values based on the first string and decrement based on the second string\n", - "* You can short circuit if the lengths of each string are not equal, len() in Python is generally O(1)\n", + "* You can short circuit if the lengths of each string are not equal, although len() in Python is generally O(1) unlike other languages like C where getting the length of a string is O(n)\n", "\n", "Complexity:\n", "* Time: O(n)\n", @@ -134,6 +141,7 @@ "source": [ "from collections import defaultdict\n", "\n", + "\n", "def unique_counts(string):\n", " dict_chars = defaultdict(int)\n", " for char in string:\n", @@ -156,15 +164,51 @@ ] }, { - "cell_type": "markdown", - "metadata": {}, + "cell_type": "code", + "execution_count": 3, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Overwriting test_permutation_solution.py\n" + ] + } + ], "source": [ - "*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand. You generally will not be asked to write a unit test like what is shown below.*" + "%%writefile test_permutation_solution.py\n", + "from nose.tools import assert_equal\n", + "\n", + "\n", + "class TestPermutation(object):\n", + " \n", + " def test_permutation(self, func):\n", + " assert_equal(func('', 'foo'), False)\n", + " assert_equal(func('Nib', 'bin'), False)\n", + " assert_equal(func('act', 'cat'), True)\n", + " assert_equal(func('a ct', 'ca t'), True)\n", + " print('Success: test_permutation')\n", + "\n", + "def main():\n", + " test = TestPermutation()\n", + " test.test_permutation(permutations)\n", + " try:\n", + " test.test_permutation(permutations_alt)\n", + " except NameError:\n", + " # Alternate solutions are only defined\n", + " # in the solutions file\n", + " pass\n", + " \n", + "if __name__ == '__main__':\n", + " main()" ] }, { "cell_type": "code", - "execution_count": 3, + "execution_count": 4, "metadata": { "collapsed": false }, @@ -179,20 +223,7 @@ } ], "source": [ - "from nose.tools import assert_equal\n", - "\n", - "class Test(object):\n", - " def test_permutation(self, func):\n", - " assert_equal(func('', 'foo'), False)\n", - " assert_equal(func('Nib', 'bin'), False)\n", - " assert_equal(func('act', 'cat'), True)\n", - " assert_equal(func('a ct', 'ca t'), True)\n", - " print('Success: test_permutation')\n", - "\n", - "if __name__ == '__main__':\n", - " test = Test()\n", - " test.test_permutation(permutations)\n", - " test.test_permutation(permutations_alt)" + "run -i test_permutation_solution.py" ] } ], diff --git a/arrays_strings/permutation/test_permutation_solution.py b/arrays_strings/permutation/test_permutation_solution.py new file mode 100644 index 0000000..430fa81 --- /dev/null +++ b/arrays_strings/permutation/test_permutation_solution.py @@ -0,0 +1,24 @@ +from nose.tools import assert_equal + + +class TestPermutation(object): + + def test_permutation(self, func): + assert_equal(func('', 'foo'), False) + assert_equal(func('Nib', 'bin'), False) + assert_equal(func('act', 'cat'), True) + assert_equal(func('a ct', 'ca t'), True) + print('Success: test_permutation') + +def main(): + test = TestPermutation() + test.test_permutation(permutations) + try: + test.test_permutation(permutations_alt) + except NameError: + # Alternate solutions are only defined + # in the solutions file + pass + +if __name__ == '__main__': + main() \ No newline at end of file