From 7d8a40adf84583085bb33d642f7ccecc1043f6c4 Mon Sep 17 00:00:00 2001 From: Donne Martin Date: Thu, 30 Mar 2017 05:43:16 -0400 Subject: [PATCH] Add str diff challenge --- arrays_strings/str_diff/__init__.py | 0 .../str_diff/str_diff_challenge.ipynb | 165 ++++++++++++++ .../str_diff/str_diff_solution.ipynb | 215 ++++++++++++++++++ arrays_strings/str_diff/test_str_diff.py | 20 ++ 4 files changed, 400 insertions(+) create mode 100644 arrays_strings/str_diff/__init__.py create mode 100644 arrays_strings/str_diff/str_diff_challenge.ipynb create mode 100644 arrays_strings/str_diff/str_diff_solution.ipynb create mode 100644 arrays_strings/str_diff/test_str_diff.py diff --git a/arrays_strings/str_diff/__init__.py b/arrays_strings/str_diff/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/arrays_strings/str_diff/str_diff_challenge.ipynb b/arrays_strings/str_diff/str_diff_challenge.ipynb new file mode 100644 index 0000000..b91c27d --- /dev/null +++ b/arrays_strings/str_diff/str_diff_challenge.ipynb @@ -0,0 +1,165 @@ +{ + "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: Find the single different char between two strings.\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", + "* Can we assume the strings are ASCII?\n", + " * Yes\n", + "* Is case important?\n", + " * The strings are lower case\n", + "* Can we assume the inputs are valid?\n", + " * No, check for None\n", + "* Can we assume this fits memory?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* None input -> TypeError\n", + "* 'abcd', 'abcde' -> 'e'\n", + "* 'aaabbcdd', 'abdbacade' -> 'e'" + ] + }, + { + "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 Solution(object):\n", + "\n", + " def find_diff(self, s, t):\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_str_diff.py\n", + "from nose.tools import assert_equal, assert_raises\n", + "\n", + "\n", + "class TestFindDiff(object):\n", + "\n", + " def test_find_diff(self):\n", + " solution = Solution()\n", + " assert_raises(TypeError, solution.find_diff, None)\n", + " assert_equal(solution.find_diff('abcd', 'abcde'), 'e')\n", + " assert_equal(solution.find_diff('aaabbcdd', 'abdbacade'), 'e')\n", + " print('Success: test_find_diff')\n", + "\n", + "\n", + "def main():\n", + " test = TestFindDiff()\n", + " test.test_find_diff()\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/arrays_strings/str_diff/str_diff_solution.ipynb b/arrays_strings/str_diff/str_diff_solution.ipynb new file mode 100644 index 0000000..90813c4 --- /dev/null +++ b/arrays_strings/str_diff/str_diff_solution.ipynb @@ -0,0 +1,215 @@ +{ + "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: Find the single different char between two strings.\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", + "* Can we assume the strings are ASCII?\n", + " * Yes\n", + "* Is case important?\n", + " * The strings are lower case\n", + "* Can we assume the inputs are valid?\n", + " * No, check for None\n", + "* Can we assume this fits memory?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* None input -> TypeError\n", + "* 'abcd', 'abcde' -> 'e'\n", + "* 'aaabbcdd', 'abdbacade' -> 'e'" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "### Dictionary\n", + "\n", + "* Keep a dictionary of seen values in s\n", + "* Loop through t, decrementing the seen values\n", + " * If the char is not there or if the decrement results in a negative value, return the char\n", + "\n", + "Complexity:\n", + "* Time: O(m+n), where m and n are the lengths of s, t\n", + "* Space: O(h), for the dict, where h is the unique chars in s\n", + "\n", + "### XOR\n", + "\n", + "* XOR the two strings, which will isolate the differing char\n", + "\n", + "Complexity:\n", + "* Time: O(m+n), where m and n are the lengths of s, t\n", + "* Space: O(1), for the dict, where h is the unique chars in s" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Code" + ] + }, + { + "cell_type": "code", + "execution_count": 1, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "class Solution(object):\n", + "\n", + " def find_diff(self, str1, str2):\n", + " if str1 is None or str2 is None:\n", + " raise TypeError('str1 or str2 cannot be None')\n", + " seen = {}\n", + " for char in str1:\n", + " if char in seen:\n", + " seen[char] += 1\n", + " else:\n", + " seen[char] = 1\n", + " for char in str2:\n", + " try:\n", + " seen[char] -= 1\n", + " except KeyError:\n", + " return char\n", + " if seen[char] < 0:\n", + " return char\n", + " return None\n", + "\n", + " def find_diff_xor(self, str1, str2):\n", + " if str1 is None or str2 is None:\n", + " raise TypeError('str1 or str2 cannot be None')\n", + " result = 0\n", + " for char in str1:\n", + " result ^= ord(char)\n", + " for char in str2:\n", + " result ^= ord(char)\n", + " return chr(result)" + ] + }, + { + "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_str_diff.py\n" + ] + } + ], + "source": [ + "%%writefile test_str_diff.py\n", + "from nose.tools import assert_equal, assert_raises\n", + "\n", + "\n", + "class TestFindDiff(object):\n", + "\n", + " def test_find_diff(self):\n", + " solution = Solution()\n", + " assert_raises(TypeError, solution.find_diff, None)\n", + " assert_equal(solution.find_diff('abcd', 'abcde'), 'e')\n", + " assert_equal(solution.find_diff('aaabbcdd', 'abdbacade'), 'e')\n", + " print('Success: test_find_diff')\n", + "\n", + "\n", + "def main():\n", + " test = TestFindDiff()\n", + " test.test_find_diff()\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_find_diff\n" + ] + } + ], + "source": [ + "%run -i test_str_diff.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/arrays_strings/str_diff/test_str_diff.py b/arrays_strings/str_diff/test_str_diff.py new file mode 100644 index 0000000..7807db3 --- /dev/null +++ b/arrays_strings/str_diff/test_str_diff.py @@ -0,0 +1,20 @@ +from nose.tools import assert_equal, assert_raises + + +class TestFindDiff(object): + + def test_find_diff(self): + solution = Solution() + assert_raises(TypeError, solution.find_diff, None) + assert_equal(solution.find_diff('abcd', 'abcde'), 'e') + assert_equal(solution.find_diff('aaabbcdd', 'abdbacade'), 'e') + print('Success: test_find_diff') + + +def main(): + test = TestFindDiff() + test.test_find_diff() + + +if __name__ == '__main__': + main() \ No newline at end of file