{
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  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0] None\t1\t\t<- free pointer\n",
      "[1] None\t2\t\t\n",
      "[2] None\t3\t\t\n",
      "[3] None\t4\t\t\n",
      "[4] None\t5\t\t\n",
      "[5] None\t6\t\t\n",
      "[6] None\t7\t\t\n",
      "[7] None\t8\t\t\n",
      "[8] None\t9\t\t\n",
      "[9] None\t-1\t\t\n",
      "=========\n",
      "[0] Steven\t-1\t\t\n",
      "[1] Xi Jinping\t0\t\t\n",
      "[2] Deng Xiaoping\t1\t\t\n",
      "[3] Chiang Kai-shek\t2\t\t\n",
      "[4] Donald Trump\t3\t<- root pointer\t\n",
      "[5] None\t6\t\t<- free pointer\n",
      "[6] None\t7\t\t\n",
      "[7] None\t8\t\t\n",
      "[8] None\t9\t\t\n",
      "[9] None\t-1\t\t\n",
      "=========\n"
     ]
    }
   ],
   "source": [
    "class LinkedList:\n",
    "    def __init__(self, l):\n",
    "        self.list = []\n",
    "        self.rootp = -1\n",
    "        self.freep = 0\n",
    "        for i in range(l):\n",
    "            self.list.append([None, i+1])\n",
    "        self.list[l-1][1] = -1\n",
    "        self.visualise()\n",
    "    def visualise(self):\n",
    "        i = 0\n",
    "        while i < len(self.list):\n",
    "            print(f\"[{i}] {self.list[i][0]}\\t{self.list[i][1]}\\t{'<- root pointer' if self.rootp == i else ''}\\t{'<- free pointer' if self.freep == i else ''}\")\n",
    "            i += 1\n",
    "        print(\"=========\")\n",
    "    def insert(self, elem): \n",
    "        if self.freep == -1:\n",
    "            print(\"Unable, not free!\")\n",
    "        self.list[self.freep][0] = elem \n",
    "        tmp = self.list[self.freep][1]\n",
    "        self.list[self.freep][1] = self.rootp \n",
    "        self.rootp = self.freep\n",
    "        self.freep = tmp\n",
    "        #self.visualise()\n",
    "new_list = LinkedList(10)\n",
    "names = [\n",
    "    \"Steven\",\n",
    "    \"Xi Jinping\",\n",
    "    \"Deng Xiaoping\",\n",
    "    \"Chiang Kai-shek\",\n",
    "    \"Donald Trump\"\n",
    "]\n",
    "for name in names:\n",
    "    new_list.insert(name)\n",
    "new_list.visualise()\n",
    "\n"
   ]
  }
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