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   "metadata": {},
   "source": [
    "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). 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 common bit manipulation operations: get_bit, set_bit, clear_bit, clear_bits_msb_to_index, clear_bits_msb_to_lsb, update_bit.\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 inputs are valid?\n",
    "    * No\n",
    "* Can we assume this fits memory?\n",
    "    * Yes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Test Cases\n",
    "\n",
    "* None as a number input -> Exception\n",
    "* Negative index -> Exception\n",
    "\n",
    "### get_bit\n",
    "    number   = 0b10001110, index = 3\n",
    "    expected = True\n",
    "### set_bit\n",
    "    number   = 0b10001110, index = 4\n",
    "    expected = 0b10011110\n",
    "### clear_bit\n",
    "    number   = 0b10001110, index = 3\n",
    "    expected = 0b10000110\n",
    "### clear_bits_msb_to_index\n",
    "    number   = 0b10001110, index = 3\n",
    "    expected = 0b00000110\n",
    "### clear_bits_index_to_lsb\n",
    "    number   = 0b10001110, index = 3\n",
    "    expected = 0b10000000\n",
    "### update_bit\n",
    "    number   = 0b10001110, index = 3, value = 1\n",
    "    expected = 0b10001110\n",
    "    number   = 0b10001110, index = 3, value = 0\n",
    "    expected = 0b10000110\n",
    "    number   = 0b10001110, index = 0, value = 1\n",
    "    expected = 0b10001111"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Algorithm\n",
    "\n",
    "Refer to the [Solution Notebook]().  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": [
    "class Bit(object):\n",
    "\n",
    "    def __init__(self, number):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def get_bit(self, index):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def set_bit(self, index):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def clear_bit(self, index):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def clear_bits_msb_to_index(self, index):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def clear_bits_index_to_lsb(self, index):\n",
    "        # TODO: Implement me\n",
    "        pass\n",
    "\n",
    "    def update_bit(self, index, value):\n",
    "        # TODO: Implement me\n",
    "        pass"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**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_bit.py\n",
    "from nose.tools import assert_equal\n",
    "\n",
    "\n",
    "class TestBit(object):\n",
    "\n",
    "    def test_bit(self):\n",
    "        number = int('10001110', base=2)\n",
    "        bit = Bit(number)\n",
    "        assert_equal(bit.get_bit(index=3), True)\n",
    "        expected = int('10011110', base=2)\n",
    "        assert_equal(bit.set_bit(index=4), expected)\n",
    "        bit = Bit(number)\n",
    "        expected = int('10000110', base=2)\n",
    "        assert_equal(bit.clear_bit(index=3), expected)\n",
    "        bit = Bit(number)\n",
    "        expected = int('00000110', base=2)\n",
    "        assert_equal(bit.clear_bits_msb_to_index(index=3), expected)\n",
    "        bit = Bit(number)\n",
    "        expected = int('10000000', base=2)\n",
    "        assert_equal(bit.clear_bits_index_to_lsb(index=3), expected)\n",
    "        bit = Bit(number)\n",
    "        assert_equal(bit.update_bit(index=3, value=1), number)\n",
    "        bit = Bit(number)\n",
    "        expected = int('10000110', base=2)\n",
    "        assert_equal(bit.update_bit(index=3, value=0), expected)\n",
    "        bit = Bit(number)\n",
    "        expected = int('10001111', base=2)\n",
    "        assert_equal(bit.update_bit(index=0, value=1), expected)\n",
    "        print('Success: test_bit')\n",
    "\n",
    "\n",
    "def main():\n",
    "    test = TestBit()\n",
    "    test.test_bit()\n",
    "\n",
    "\n",
    "if __name__ == '__main__':\n",
    "    main()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Solution Notebook\n",
    "\n",
    "Review the [Solution Notebook]() for a discussion on algorithms and code solutions."
   ]
  }
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