interactive-coding-challenges/arrays_strings/reverse_string/reverse_string_challenge.ipynb

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{
"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/interactive-coding-challenges)."
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]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Challenge Notebook"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Problem: Implement a function to reverse a string (a list of characters), in-place.\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",
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"* Can we assume the string is ASCII?\n",
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" * Yes\n",
" * Note: Unicode strings could require special handling depending on your language\n",
"* Since we need to do this in-place, it seems we cannot use the slice operator or the reversed function?\n",
" * Correct\n",
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"* Since Python string are immutable, can we use a list of characters instead?\n",
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" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"* None -> None\n",
"* [''] -> ['']\n",
"* ['f', 'o', 'o', ' ', 'b', 'a', 'r'] -> ['r', 'a', 'b', ' ', 'o', 'o', 'f']"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
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"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/reverse_string/reverse_string_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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]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Code"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
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"outputs": [],
"source": [
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"class ReverseString(object):\n",
"\n",
" def reverse(self, chars):\n",
" # TODO: Implement me\n",
" pass"
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]
},
{
"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": {},
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"outputs": [],
"source": [
"# %load test_reverse_string.py\n",
"import unittest\n",
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"\n",
"\n",
"class TestReverse(unittest.TestCase):\n",
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"\n",
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" def test_reverse(self, func):\n",
" self.assertEqual(func(None), None)\n",
" self.assertEqual(func(['']), [''])\n",
" self.assertEqual(func(\n",
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" ['f', 'o', 'o', ' ', 'b', 'a', 'r']),\n",
" ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
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" print('Success: test_reverse')\n",
"\n",
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" def test_reverse_inplace(self, func):\n",
" target_list = ['f', 'o', 'o', ' ', 'b', 'a', 'r']\n",
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" func(target_list)\n",
" self.assertEqual(target_list, ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
" print('Success: test_reverse_inplace')\n",
"\n",
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"\n",
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"def main():\n",
" test = TestReverse()\n",
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" reverse_string = ReverseString()\n",
" test.test_reverse(reverse_string.reverse)\n",
" test.test_reverse_inplace(reverse_string.reverse)\n",
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"\n",
"\n",
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"if __name__ == '__main__':\n",
" main()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Solution Notebook\n",
"\n",
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"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/reverse_string/reverse_string_solution.ipynb) for a discussion on algorithms and code solutions."
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]
}
],
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"display_name": "Python 3",
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"language": "python",
"name": "python3"
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"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
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"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
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