From 895011b68528a886eedde8d7f30ec58ba586d382 Mon Sep 17 00:00:00 2001
From: Donne Martin <donne.martin@gmail.com>
Date: Sun, 12 Jun 2016 23:19:09 -0400
Subject: [PATCH] Polish unique chars challenge and solution

Add None input test case.  Update constraints.
---
 .../unique_chars/test_unique_chars.py         |  1 +
 .../unique_chars/unique_chars_challenge.ipynb | 18 ++++++++------
 .../unique_chars/unique_chars_solution.ipynb  | 24 +++++++++++++------
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/arrays_strings/unique_chars/test_unique_chars.py b/arrays_strings/unique_chars/test_unique_chars.py
index 5dd6016..5219cf5 100644
--- a/arrays_strings/unique_chars/test_unique_chars.py
+++ b/arrays_strings/unique_chars/test_unique_chars.py
@@ -4,6 +4,7 @@ from nose.tools import assert_equal
 class TestUniqueChars(object):
 
     def test_unique_chars(self, func):
+        assert_equal(func(None), False)
         assert_equal(func(''), True)
         assert_equal(func('foo'), False)
         assert_equal(func('bar'), True)
diff --git a/arrays_strings/unique_chars/unique_chars_challenge.ipynb b/arrays_strings/unique_chars/unique_chars_challenge.ipynb
index 91ea17c..1f391ff 100644
--- a/arrays_strings/unique_chars/unique_chars_challenge.ipynb
+++ b/arrays_strings/unique_chars/unique_chars_challenge.ipynb
@@ -34,12 +34,14 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "* Can you 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",
     "* Can we assume this is case sensitive?\n",
     "    * Yes\n",
-    "* Can you use additional data structures?\n",
+    "* Can we use additional data structures?\n",
+    "    * Yes\n",
+    "* Can we assume this fits in memory?\n",
     "    * Yes"
    ]
   },
@@ -49,6 +51,7 @@
    "source": [
     "## Test Cases\n",
     "\n",
+    "* None -> False\n",
     "* '' -> True\n",
     "* 'foo' -> False\n",
     "* 'bar' -> True"
@@ -112,6 +115,7 @@
     "class TestUniqueChars(object):\n",
     "\n",
     "    def test_unique_chars(self, func):\n",
+    "        assert_equal(func(None), False)\n",
     "        assert_equal(func(''), True)\n",
     "        assert_equal(func('foo'), False)\n",
     "        assert_equal(func('bar'), True)\n",
@@ -146,21 +150,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/arrays_strings/unique_chars/unique_chars_solution.ipynb b/arrays_strings/unique_chars/unique_chars_solution.ipynb
index 4c0c787..38def41 100644
--- a/arrays_strings/unique_chars/unique_chars_solution.ipynb
+++ b/arrays_strings/unique_chars/unique_chars_solution.ipynb
@@ -37,12 +37,14 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "* Can you 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",
     "* Can we assume this is case sensitive?\n",
     "    * Yes\n",
-    "* Can you use additional data structures?  \n",
+    "* Can we use additional data structures?\n",
+    "    * Yes\n",
+    "* Can we assume this fits in memory?\n",
     "    * Yes"
    ]
   },
@@ -52,6 +54,7 @@
    "source": [
     "## Test Cases\n",
     "\n",
+    "* None -> False\n",
     "* '' -> True\n",
     "* 'foo' -> False\n",
     "* 'bar' -> True"
@@ -91,6 +94,8 @@
    "outputs": [],
    "source": [
     "def unique_chars(string):\n",
+    "    if string is None:\n",
+    "        return False\n",
     "    return len(set(string)) == len(string)"
    ]
   },
@@ -134,6 +139,8 @@
    "outputs": [],
    "source": [
     "def unique_chars_hash(string):\n",
+    "    if string is None:\n",
+    "        return False\n",
     "    chars_set = set()\n",
     "    for char in string:\n",
     "        if char in chars_set:\n",
@@ -178,6 +185,8 @@
    "outputs": [],
    "source": [
     "def unique_chars_inplace(string):\n",
+    "    if string is None:\n",
+    "        return False\n",
     "    for char in string:\n",
     "        if string.count(char) > 1:\n",
     "            return False\n",
@@ -214,6 +223,7 @@
     "class TestUniqueChars(object):\n",
     "\n",
     "    def test_unique_chars(self, func):\n",
+    "        assert_equal(func(None), False)\n",
     "        assert_equal(func(''), True)\n",
     "        assert_equal(func('foo'), False)\n",
     "        assert_equal(func('bar'), True)\n",
@@ -260,21 +270,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,