interactive-coding-challenges/online_judges/assign_cookies/assign_cookies_solution.ipynb

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    "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",
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   "source": [
    "# Solution Notebook"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Problem: Assign Cookies.\n",
    "\n",
    "See the [LeetCode](https://leetcode.com/problems/assign-cookies/) problem page.\n",
    "\n",
    "Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a cookie that the child will be content with; and each cookie j has a size sj. If sj >= gi, we can assign the cookie j to the child i, and the child i will be content. Your goal is to maximize the number of your content children and output the maximum number.\n",
    "\n",
    "Note:\n",
    "You may assume the greed factor is always positive. \n",
    "You cannot assign more than one cookie to one child.\n",
    "\n",
    "Example 1:\n",
    "Input: [1,2,3], [1,1]\n",
    "\n",
    "Output: 1\n",
    "\n",
    "Explanation: You have 3 children and 2 cookies. The greed factors of 3 children are 1, 2, 3. \n",
    "And even though you have 2 cookies, since their size is both 1, you could only make the child whose greed factor is 1 content.\n",
    "You need to output 1.\n",
    "Example 2:\n",
    "Input: [1,2], [1,2,3]\n",
    "\n",
    "Output: 2\n",
    "\n",
    "Explanation: You have 2 children and 3 cookies. The greed factors of 2 children are 1, 2. \n",
    "You have 3 cookies and their sizes are big enough to gratify all of the children, \n",
    "You need to output 2.\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",
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   "source": [
    "## Constraints\n",
    "\n",
    "* Are the inputs two list(int), one for greed factor and the other for cookie size?\n",
    "    * Yes\n",
    "* Are the inputs are sorted increasing order?\n",
    "    * No\n",
    "* Can we change inputs themselves, or do we need to make a copy?\n",
    "    * You can change them\n",
    "* Is the output an int?\n",
    "    * Yes\n",
    "* Is the greed factor always >= 1?\n",
    "    * Yes\n",
    "* Can we assume the inputs are valid?\n",
    "    * No, check for None\n",
    "* Can we assume this fits memory?\n",
    "    * Yes"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Test Cases\n",
    "\n",
    "<pre>\n",
    "* None input -> TypeError\n",
    "[1, 2, 3], [1, 1] -> 1\n",
    "[1, 2], [1, 2, 3] -> 2\n",
    "[7, 8, 9, 10], [5, 6, 7, 8] -> 2\n",
    "</pre>"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Algorithm\n",
    "\n",
    "* Sort the inputs\n",
    "* We'll keep an index to the current greed factor\n",
    "* For each cookie\n",
    "    * Assign it to a child if its size >= the child's greed factor\n",
    "        * Increment result counter\n",
    "        * Increment the index to the greed factor\n",
    "            * Careful of this index going out of bounds\n",
    "* Return the result counter\n",
    "\n",
    "Complexity:\n",
    "* Time: O(n log n) for the sort\n",
    "* Space: O(1), assuming the sort is in-place"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
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   "outputs": [],
   "source": [
    "class Solution(object):\n",
    "\n",
    "    def find_content_children(self, greed_indices, cookie_sizes):\n",
    "        if greed_indices is None or cookie_sizes is None:\n",
    "            raise TypeError('greed_indices or cookie_sizes cannot be None')\n",
    "        if not greed_indices or not cookie_sizes:\n",
    "            return 0\n",
    "        greed_indices.sort()\n",
    "        cookie_sizes.sort()\n",
    "        greed_index = 0\n",
    "        num_children = 0\n",
    "        for size in cookie_sizes:\n",
    "            if greed_index >= len(greed_indices):\n",
    "                break\n",
    "            if size >= greed_indices[greed_index]:\n",
    "                num_children += 1\n",
    "                greed_index += 1\n",
    "        return num_children"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Overwriting test_assign_cookie.py\n"
     ]
    }
   ],
   "source": [
    "%%writefile test_assign_cookie.py\n",
    "from nose.tools import assert_equal, assert_raises\n",
    "\n",
    "\n",
    "class TestAssignCookie(object):\n",
    "\n",
    "    def test_assign_cookie(self):\n",
    "        solution = Solution()\n",
    "        assert_raises(TypeError, solution.find_content_children, None, None)\n",
    "        assert_equal(solution.find_content_children([1, 2, 3], \n",
    "                                                    [1, 1]), 1)\n",
    "        assert_equal(solution.find_content_children([1, 2], \n",
    "                                                    [1, 2, 3]), 2)\n",
    "        assert_equal(solution.find_content_children([7, 8, 9, 10], \n",
    "                                                    [5, 6, 7, 8]), 2)\n",
    "        print('Success: test_find_content_children')\n",
    "\n",
    "\n",
    "def main():\n",
    "    test = TestAssignCookie()\n",
    "    test.test_assign_cookie()\n",
    "\n",
    "\n",
    "if __name__ == '__main__':\n",
    "    main()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Success: test_find_content_children\n"
     ]
    }
   ],
   "source": [
    "%run -i test_assign_cookie.py"
   ]
  }
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