interactive-coding-challenges/online_judges/math_ops/math_ops_solution.ipynb

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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)."
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Solution Notebook"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Problem: Create a class with an insert method to insert an int to a list.  It should also support calculating the max, min, mean, and mode in O(1).\n",
    "\n",
    "* [Constraints](#Constraints)\n",
    "* [Test Cases](#Test-Cases)\n",
    "* [Algorithm](#Algorithm)\n",
    "* [Code](#Code)\n",
    "* [Unit Test](#Unit-Test)"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Constraints\n",
    "\n",
    "* Can we assume the inputs are valid?\n",
    "    * No\n",
    "* Is there a range of inputs?\n",
    "    * 0 <= item <= 100\n",
    "* Should mean return a float?\n",
    "    * Yes\n",
    "* Should the other results return an int?\n",
    "    * Yes\n",
    "* If there are multiple modes, what do we return?\n",
    "    * Any of the modes\n",
    "* Can we assume this fits memory?\n",
    "    * Yes"
   ]
  },
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   "cell_type": "markdown",
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   "source": [
    "## Test Cases\n",
    "\n",
    "* None -> TypeError\n",
    "* [] -> ValueError\n",
    "* [5, 2, 7, 9, 9, 2, 9, 4, 3, 3, 2]\n",
    "    * max: 9\n",
    "    * min: 2\n",
    "    * mean: 55\n",
    "    * mode: 9 or 2"
   ]
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   "cell_type": "markdown",
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   "source": [
    "## Algorithm\n",
    "\n",
    "Return the input, val\n",
    "\n",
    "Complexity:\n",
    "* Time: O(1)\n",
    "* Space: O(1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
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   "outputs": [],
   "source": [
    "from __future__ import division\n",
    "\n",
    "\n",
    "class Solution(object):\n",
    "\n",
    "    def __init__(self, upper_limit=100):\n",
    "        self.max = None\n",
    "        self.min = None\n",
    "        # Mean\n",
    "        self.num_items = 0\n",
    "        self.running_sum = 0\n",
    "        self.mean = None\n",
    "        # Mode\n",
    "        self.array = [0] * (upper_limit+1)\n",
    "        self.mode_ocurrences = 0\n",
    "        self.mode = None\n",
    "\n",
    "    def insert(self, val):\n",
    "        if val is None:\n",
    "            raise TypeError('val cannot be None')\n",
    "        if self.max is None or val > self.max:\n",
    "            self.max = val\n",
    "        if self.min is None or val < self.min:\n",
    "            self.min = val\n",
    "        # Calculate the mean\n",
    "        self.num_items += 1\n",
    "        self.running_sum += val\n",
    "        self.mean = self.running_sum / self.num_items\n",
    "        # Calculate the mode\n",
    "        self.array[val] += 1\n",
    "        if self.array[val] > self.mode_ocurrences:\n",
    "            self.mode_ocurrences = self.array[val]\n",
    "            self.mode = val"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Overwriting test_math_ops.py\n"
     ]
    }
   ],
   "source": [
    "%%writefile test_math_ops.py\n",
    "from nose.tools import assert_equal, assert_true, assert_raises\n",
    "\n",
    "\n",
    "class TestMathOps(object):\n",
    "\n",
    "    def test_math_ops(self):\n",
    "        solution = Solution()\n",
    "        assert_raises(TypeError, solution.insert, None)\n",
    "        solution.insert(5)\n",
    "        solution.insert(2)\n",
    "        solution.insert(7)\n",
    "        solution.insert(9)\n",
    "        solution.insert(9)\n",
    "        solution.insert(2)\n",
    "        solution.insert(9)\n",
    "        solution.insert(4)\n",
    "        solution.insert(3)\n",
    "        solution.insert(3)\n",
    "        solution.insert(2)\n",
    "        assert_equal(solution.max, 9)\n",
    "        assert_equal(solution.min, 2)\n",
    "        assert_equal(solution.mean, 5)\n",
    "        assert_true(solution.mode in (2, 9))\n",
    "        print('Success: test_math_ops')\n",
    "\n",
    "\n",
    "def main():\n",
    "    test = TestMathOps()\n",
    "    test.test_math_ops()\n",
    "\n",
    "\n",
    "if __name__ == '__main__':\n",
    "    main()"
   ]
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    {
     "ename": "AssertionError",
     "evalue": "False is not true",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m                      Traceback (most recent call last)",
      "\u001b[0;32m/Users/donnemartin/Dev/github/sources/interactive-coding-challenges/online_judges/math_ops/test_math_ops.py\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m     31\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     32\u001b[0m \u001b[0;32mif\u001b[0m \u001b[0m__name__\u001b[0m \u001b[0;34m==\u001b[0m \u001b[0;34m'__main__'\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 33\u001b[0;31m     \u001b[0mmain\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m/Users/donnemartin/Dev/github/sources/interactive-coding-challenges/online_judges/math_ops/test_math_ops.py\u001b[0m in \u001b[0;36mmain\u001b[0;34m()\u001b[0m\n\u001b[1;32m     27\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mmain\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     28\u001b[0m     \u001b[0mtest\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mTestMathOps\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 29\u001b[0;31m     \u001b[0mtest\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mtest_math_ops\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     30\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     31\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m/Users/donnemartin/Dev/github/sources/interactive-coding-challenges/online_judges/math_ops/test_math_ops.py\u001b[0m in \u001b[0;36mtest_math_ops\u001b[0;34m(self)\u001b[0m\n\u001b[1;32m     21\u001b[0m         \u001b[0massert_equal\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mmin\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     22\u001b[0m         \u001b[0massert_equal\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mmean\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m5\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 23\u001b[0;31m         \u001b[0massert_true\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0msolution\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mmode\u001b[0m \u001b[0;32min\u001b[0m \u001b[0;34m(\u001b[0m\u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m92\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     24\u001b[0m         \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'Success: test_math_ops'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     25\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m/Users/donnemartin/.pyenv/versions/3.5.0/lib/python3.5/unittest/case.py\u001b[0m in \u001b[0;36massertTrue\u001b[0;34m(self, expr, msg)\u001b[0m\n\u001b[1;32m    672\u001b[0m         \u001b[0;32mif\u001b[0m \u001b[0;32mnot\u001b[0m \u001b[0mexpr\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    673\u001b[0m             \u001b[0mmsg\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_formatMessage\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmsg\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m\"%s is not true\"\u001b[0m \u001b[0;34m%\u001b[0m \u001b[0msafe_repr\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mexpr\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 674\u001b[0;31m             \u001b[0;32mraise\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mfailureException\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmsg\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m    675\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    676\u001b[0m     \u001b[0;32mdef\u001b[0m \u001b[0m_formatMessage\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mmsg\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mstandardMsg\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mAssertionError\u001b[0m: False is not true"
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   "source": [
    "%run -i test_math_ops.py"
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