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   "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": {
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   },
   "source": [
    "# Challenge Notebook"
   ]
  },
  {
   "cell_type": "markdown",
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   },
   "source": [
    "## Problem: Remove specified characters in a string\t\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)"
   ]
  },
  {
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   "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",
    "* Can we assume this is case sensitive?\n",
    "    * Yes\n",
    "* Can we use additional data structures?\n",
    "    * Yes\n",
    "* Can we assume this fits in memory?\n",
    "    * Yes"
   ]
  },
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   "source": [
    "## Test Cases\n",
    "\n",
    "String = 'Python is great'\n",
    "chars -> This is the characters to remove from String\n",
    "\n",
    "* chars = None -> False\n",
    "* chars = '' -> 'Python is great'\n",
    "* chars = 'y' -> 'Pthon is great'\n",
    "* chars = 'tp' -> 'yhon is grea'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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   },
   "source": [
    "## Algorithm\n",
    "\n",
    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/remove_chars/remove_chars_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": {
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   "source": [
    "## Code"
   ]
  },
  {
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   "source": [
    "class RemoveChars(object):\n",
    "\n",
    "    def remove_chars(self, string, chars):\n",
    "        # TODO: Implement me\n",
    "        pass"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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    "editable": true
   },
   "source": [
    "**The following unit test is expected to fail until you solve the challenge.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "# %load test_remove_chars.py\n",
    "from nose.tools import assert_equal\n",
    "\n",
    "class TestRemoveChars(object):\n",
    "\n",
    "    def test_remove_chars(self, string, func):\n",
    "        assert_equal(func(string, None), False)\n",
    "        assert_equal(func(string, ''), 'Python is great')\n",
    "        assert_equal(func(string, 'y'), 'Pthon is great')\n",
    "        assert_equal(func(string, 'tP'), 'yhon is grea')\n",
    "        print('Success: test_remove_chars')\n",
    "\n",
    "\n",
    "def main():\n",
    "    test = TestRemoveChars()\n",
    "    remove_chars = RemoveChars()\n",
    "    string = 'Python is great'\n",
    "    test.test_remove_chars(string, remove_chars.remove_chars)\n",
    "    \n",
    "\n",
    "if __name__ == '__main__':\n",
    "    main()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Solution Notebook\n",
    "\n",
    "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/remove_chars/remove_chars_solution.ipynb) for a discussion on algorithms and code solutions."
   ]
  }
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