Add solution to challenge reverse words

arrays_strings/reverse_words/reverse_words_challenge.ipynb

@@ -92,16 +92,6 @@
     "## Unit Test"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {
-    "deletable": true,
-    "editable": true
-   },
-   "source": [
-    "**The following unit test is expected to fail until you solve the challenge.**"
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -110,8 +100,7 @@
    },
    "outputs": [],
    "source": [
-    "\n",
+    "# %load test_reverse_words.py\n",
-    "# %load test_reverse_string.py\n",
     "from nose.tools import assert_equal\n",
     "\n",
     "\n",
@@ -140,9 +129,9 @@
  "metadata": {
   "celltoolbar": "Edit Metadata",
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 2",
    "language": "python",
-   "name": "python3"
+   "name": "python2"
   },
   "language_info": {
    "codemirror_mode": {
@@ -154,7 +143,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.12"
   }
  },
  "nbformat": 4,

arrays_strings/reverse_words/reverse_words_challenge.py

@@ -0,0 +1,37 @@
+class ReverseWords:
+
+    def reverse(self, string):
+        if string is None:
+            return None
+        if string == ['']:
+            return ['']
+        buff_w = []  # buffer for substrings
+        substring = []  # substring
+        new_string = []  # new string with reverses words
+        for i in range(len(string)):
+            if(string[i] == ' '):
+                for h in range(len(buff_w) - 1, -1, -1):
+                    substring.append(buff_w[h])
+                for j in range(len(substring)):
+                    new_string.append(substring[j])
+                substring = []
+                buff_w = []
+            else:
+                buff_w.append(string[i])
+                if(i == (len(string) - 1)):
+                    new_string.append(' ')
+                    for h in range(len(buff_w) - 1, -1, -1):
+                        substring.append(buff_w[h])
+                    for j in range(len(substring)):
+                        new_string.append(substring[j])
+        return new_string
+
+
+def main():
+    R = ReverseWords()
+    result = R.reverse('foo bar')
+    print(result)
+
+
+if __name__ == "__main__":
+    main()

arrays_strings/reverse_words/reverse_words_challenge_solution.ipynb

@@ -0,0 +1,187 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This notebook was prepared by [eamanu](http://github.com/eamanu). 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 a function to reverse words within a 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",
+    "* Can we assume the string is ASCII?\n",
+    "    * 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",
+    "* Since Python string are immutable, can we use a list of characters instead?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* None -> None\n",
+    "* [''] -> ['']\n",
+    "* ['f', 'o', 'o', ' ', 'b', 'a', 'r'] -> ['o', 'o', 'f', ' ', 'r', 'a', 'b']"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "* First if String is None\n",
+    "    * Return None\n",
+    "* If String is ['']\n",
+    "    * Return ['']\n",
+    "* Go throught the string and we append in a buffer\n",
+    "* IF the actual char is ' ' we reverse the buffer and put into a new string (the solution)\n",
+    "* Repeat until the finished.\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "class ReverseWords:\n",
+    "\n",
+    "    def reverse(self, string):\n",
+    "        if string is None:\n",
+    "            return None\n",
+    "        if string == ['']:\n",
+    "            return ['']\n",
+    "        buff_w = []  # buffer for substrings\n",
+    "        substring = []  # substring\n",
+    "        new_string = []  # new string with reverses words\n",
+    "        for i in range(len(string)):\n",
+    "            if(string[i] == ' '):\n",
+    "                for h in range(len(buff_w) - 1, -1, -1):\n",
+    "                    substring.append(buff_w[h])\n",
+    "                for j in range(len(substring)):\n",
+    "                    new_string.append(substring[j])\n",
+    "                substring = []\n",
+    "                buff_w = []\n",
+    "            else:\n",
+    "                buff_w.append(string[i])\n",
+    "                if(i == (len(string) - 1)):\n",
+    "                    new_string.append(' ')\n",
+    "                    for h in range(len(buff_w) - 1, -1, -1):\n",
+    "                        substring.append(buff_w[h])\n",
+    "                    for j in range(len(substring)):\n",
+    "                        new_string.append(substring[j])\n",
+    "        return new_string\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Success: test_reverse\n"
+     ]
+    }
+   ],
+   "source": [
+    "# %load test_reverse_words.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestReverseWords(object):\n",
+    "\n",
+    "    def test_reverse(self, func):\n",
+    "        assert_equal(func(None), None)\n",
+    "        assert_equal(func(['']), [''])\n",
+    "        assert_equal(func(\n",
+    "            ['f', 'o', 'o', ' ', 'b', 'a', 'r']),\n",
+    "            ['o', 'o', 'f', ' ', 'r', 'a', 'b'])\n",
+    "        print('Success: test_reverse')\n",
+    "        \n",
+    "        \n",
+    "def main():\n",
+    "    test = TestReverseWords()\n",
+    "    reverse_string = ReverseWords()\n",
+    "    test.test_reverse(reverse_string.reverse)\n",
+    "\n",
+    "    \n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  }
+ ],
+ "metadata": {
+  "celltoolbar": "Edit 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": "3.5.2"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

arrays_strings/reverse_words/test_reverse_words.py

@@ -0,0 +1,22 @@
+from nose.tools import assert_equal
+
+
+class TestReverseWords(object):
+
+    def test_reverse(self, func):
+        assert_equal(func(None), None)
+        assert_equal(func(['']), [''])
+        assert_equal(func(
+            ['f', 'o', 'o', ' ', 'b', 'a', 'r']),
+            ['o', 'o', 'f', ' ', 'r', 'a', 'b'])
+        print('Success: test_reverse')
+
+
+def main():
+    test = TestReverseWords()
+    reverse_string = ReverseWords()
+    test.test_reverse(reverse_string.reverse)
+
+
+if __name__ == '__main__':
+    main()