diff --git a/arrays_strings/replace_char/replace_char_challenge.ipynb b/arrays_strings/replace_char/replace_char_challenge.ipynb
new file mode 100644
index 0000000..927416c
--- /dev/null
+++ b/arrays_strings/replace_char/replace_char_challenge.ipynb
@@ -0,0 +1,177 @@
+{
+ "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: Given a string, replace all spaces with '%20', 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",
+ "*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 there enough space in the data structure for this operation?\n",
+ " * Yes\n",
+ "* Since Python strings are immutable and we are asked to do this in-place, can I use a bytearray or a list instead?\n",
+ " * Yes"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Test Cases\n",
+ "\n",
+ "* None -> None\n",
+ "* ' ' -> '%20'\n",
+ "* ' foo bar ' -> '%20foo%20bar%20'\n",
+ "* 'foo' -> 'foo'"
+ ]
+ },
+ {
+ "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/replace_char/replace_char_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 encode_spaces(string, length):\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_replace_char.py\n",
+ "from nose.tools import assert_equal\n",
+ "\n",
+ "\n",
+ "class TestReplace(object):\n",
+ " \n",
+ " def test_replace_char(self, func):\n",
+ " # | are used to satisfy the constraint that\n",
+ " # there is enough space in the string to\n",
+ " # replace ' ' with '%20'\n",
+ " # For each space, add two ||\n",
+ " str0 = None\n",
+ " str1 = bytearray(' ||')\n",
+ " str2 = bytearray(' foo bar ||||||')\n",
+ " str3 = bytearray('foo')\n",
+ " func(str0, 0)\n",
+ " func(str1, 1)\n",
+ " func(str2, 9)\n",
+ " func(str3, 3)\n",
+ " assert_equal(str0, None)\n",
+ " assert_equal(str1, '%20')\n",
+ " assert_equal(str2, '%20foo%20bar%20')\n",
+ " assert_equal(str3, 'foo')\n",
+ " print('Success: test_replace_char')\n",
+ "\n",
+ "def main():\n",
+ " test = TestReplace()\n",
+ " test.test_replace_char(encode_spaces)\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/replace_char/replace_char_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/replace_char/replace_char_solution.ipynb b/arrays_strings/replace_char/replace_char_solution.ipynb
index cd12f74..e2cdf36 100644
--- a/arrays_strings/replace_char/replace_char_solution.ipynb
+++ b/arrays_strings/replace_char/replace_char_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"
]
},
{
@@ -18,7 +25,8 @@
"* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n",
"* [Pythonic-Code: Not In-Place](#Pythonic-Code:-Not-In-Place)\n",
- "* [Unit Test](#Unit-Test)"
+ "* [Unit Test](#Unit-Test)\n",
+ "* [Solution Notebook](#Solution-Notebook)"
]
},
{
@@ -27,12 +35,14 @@
"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 there enough space in the data structure for this operation?\n",
+ " * Yes\n",
+ "* Since Python strings are immutable and we are asked to do this in-place, can I use a bytearray or a list instead?\n",
" * Yes"
]
},
@@ -42,7 +52,7 @@
"source": [
"## Test Cases\n",
"\n",
- "* NULL->NULL\n",
+ "* None -> None\n",
"* ' ' -> '%20'\n",
"* ' foo bar ' -> '%20foo%20bar%20'\n",
"* 'foo' -> 'foo'"
@@ -54,9 +64,7 @@
"source": [
"## Algorithm\n",
"\n",
- "Since Python strings are immutable, we'll use a bytearray instead to exercise in-place string manipulation as you would get with a C string (which is null terminated, as seen in the diagram below). Python does not use a null-terminator.\n",
- "\n",
- "\n",
+ "Since Python strings are immutable, we'll use a bytearray instead to exercise in-place string manipulation as you would get with a C string.\n",
"\n",
"* Count the number of spaces in the bytearray\n",
"* Determine the new bytearray length\n",
@@ -125,6 +133,7 @@
"source": [
"import re\n",
"\n",
+ "\n",
"def encode_spaces_alt(string):\n",
" return re.sub(' ', '%20', string)\n",
"\n",
@@ -139,13 +148,6 @@
"## Unit Test"
]
},
- {
- "cell_type": "markdown",
- "metadata": {},
- "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.*"
- ]
- },
{
"cell_type": "code",
"execution_count": 3,
@@ -157,15 +159,21 @@
"name": "stdout",
"output_type": "stream",
"text": [
- "Success: test_replace_char\n"
+ "Overwriting test_replace_char.py\n"
]
}
],
"source": [
+ "%%writefile test_replace_char.py\n",
"from nose.tools import assert_equal\n",
"\n",
- "class Test(object):\n",
+ "\n",
+ "class TestReplace(object):\n",
+ " \n",
" def test_replace_char(self, func):\n",
+ " # | are used to satisfy the constraint that\n",
+ " # there is enough space in the string to replace\n",
+ " # ' ' with '%20'\n",
" str0 = None\n",
" str1 = bytearray(' ||')\n",
" str2 = bytearray(' foo bar ||||||')\n",
@@ -180,9 +188,31 @@
" assert_equal(str3, 'foo')\n",
" print('Success: test_replace_char')\n",
"\n",
+ "def main():\n",
+ " test = TestReplace()\n",
+ " test.test_replace_char(encode_spaces)\n",
+ " \n",
"if __name__ == '__main__':\n",
- " test = Test()\n",
- " test.test_replace_char(encode_spaces)"
+ " main()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 4,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Success: test_replace_char\n"
+ ]
+ }
+ ],
+ "source": [
+ "run -i test_replace_char.py"
]
}
],
diff --git a/arrays_strings/replace_char/test_replace_char.py b/arrays_strings/replace_char/test_replace_char.py
new file mode 100644
index 0000000..1d86f66
--- /dev/null
+++ b/arrays_strings/replace_char/test_replace_char.py
@@ -0,0 +1,29 @@
+from nose.tools import assert_equal
+
+
+class TestReplace(object):
+
+ def test_replace_char(self, func):
+ # | are used to satisfy the constraint that
+ # there is enough space in the string to replace
+ # ' ' with '%20'
+ str0 = None
+ str1 = bytearray(' ||')
+ str2 = bytearray(' foo bar ||||||')
+ str3 = bytearray('foo')
+ func(str0, 0)
+ func(str1, 1)
+ func(str2, 9)
+ func(str3, 3)
+ assert_equal(str0, None)
+ assert_equal(str1, '%20')
+ assert_equal(str2, '%20foo%20bar%20')
+ assert_equal(str3, 'foo')
+ print('Success: test_replace_char')
+
+def main():
+ test = TestReplace()
+ test.test_replace_char(encode_spaces)
+
+if __name__ == '__main__':
+ main()
\ No newline at end of file