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   "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)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Challenge Notebook"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Problem: Determine if a string is a permutation of another 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",
    "* Is whitespace important?\n",
    "    * Yes\n",
    "* Is this case sensitive?  'Nib', 'bin' is not a match?\n",
    "    * Yes\n",
    "* Can we use additional data structures?\n",
    "    * Yes\n",
    "* Can we assume this fits in memory?\n",
    "    * Yes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Test Cases\n",
    "\n",
    "* One or more None inputs -> False\n",
    "* One or more empty strings -> False\n",
    "* 'Nib', 'bin' -> False\n",
    "* 'act', 'cat' -> True\n",
    "* 'a ct', 'ca t' -> True"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Algorithm\n",
    "\n",
    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/permutation/permutation_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,
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   "outputs": [],
   "source": [
    "class Permutations(object):\n",
    "\n",
    "    def is_permutation(self, str1, str2):\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": {
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   "outputs": [],
   "source": [
    "# %load test_permutation_solution.py\n",
    "from nose.tools import assert_equal\n",
    "\n",
    "\n",
    "class TestPermutation(object):\n",
    "\n",
    "    def test_permutation(self, func):\n",
    "        assert_equal(func(None, 'foo'), False)\n",
    "        assert_equal(func('', 'foo'), False)\n",
    "        assert_equal(func('Nib', 'bin'), False)\n",
    "        assert_equal(func('act', 'cat'), True)\n",
    "        assert_equal(func('a ct', 'ca t'), True)\n",
    "        print('Success: test_permutation')\n",
    "\n",
    "\n",
    "def main():\n",
    "    test = TestPermutation()\n",
    "    permutations = Permutations()\n",
    "    test.test_permutation(permutations.is_permutation)\n",
    "    try:\n",
    "        permutations_alt = PermutationsAlt()\n",
    "        test.test_permutation(permutations_alt.is_permutation)\n",
    "    except NameError:\n",
    "        # Alternate solutions are only defined\n",
    "        # in the solutions file\n",
    "        pass\n",
    "\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/interactive-coding-challenges/blob/master/arrays_strings/permutation/permutation_solution.ipynb) for a discussion on algorithms and code solutions."
   ]
  }
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