Circular Linked List.ipynb

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  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Node:\n",
    "    def __init__(self,data):\n",
    "        self.data = data\n",
    "        self.next = None"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [],
   "source": [
    "class CircularLinkedList:\n",
    "    def __init__(self):\n",
    "        self.head = None\n",
    "    \n",
    "    def prepend(self,data):\n",
    "        new_node = Node(data)\n",
    "        cur = self.head\n",
    "        new_node.next = self.head\n",
    "        if self.head is None:\n",
    "            new_node.next = new_node\n",
    "        else:\n",
    "            while cur.next != self.head:\n",
    "                cur = cur.next\n",
    "            cur.next = new_node\n",
    "        self.head = new_node\n",
    "    \n",
    "    def append(self,data):\n",
    "        if self.head is None:\n",
    "            self.head = Node(data)\n",
    "            self.head.next = self.head\n",
    "        else:\n",
    "            new_node = Node(data)\n",
    "            cur = self.head\n",
    "            while cur.next != self.head:\n",
    "                cur = cur.next\n",
    "            cur.next = new_node\n",
    "            new_node.next = self.head\n",
    "    \n",
    "    def remove(self,data):\n",
    "        if self.head.data == data:\n",
    "            cur = self.head\n",
    "            while cur.next != self.head:\n",
    "                cur = cur.next\n",
    "            cur.next = self.head.next\n",
    "            self.head = self.head.next\n",
    "        \n",
    "        else:\n",
    "            cur = self.head\n",
    "            prev = None\n",
    "            while cur.next != self.head:\n",
    "                prev = cur\n",
    "                cur = cur.next\n",
    "                if cur.data == data:\n",
    "                    prev.next = cur.next\n",
    "                    break\n",
    "    \n",
    "    def __len__(self):\n",
    "        cur = self.head\n",
    "        count = 0\n",
    "        while cur:\n",
    "            count += 1\n",
    "            cur = cur.next\n",
    "            if cur == self.head:\n",
    "                break\n",
    "        return count\n",
    "    \n",
    "    def split_clist(self):\n",
    "        size = len(self)\n",
    "        if size == 0 :\n",
    "            return None\n",
    "        elif size == 1:\n",
    "            return self.head\n",
    "        mid = size//2\n",
    "        count = 0\n",
    "        prev = None\n",
    "        cur = self.head\n",
    "        while cur and count < mid:\n",
    "            count += 1\n",
    "            prev = cur\n",
    "            cur = cur.next\n",
    "        prev.next = self.head\n",
    "        \n",
    "        split_clist = CircularLinkedList()\n",
    "        while cur.next != self.head:\n",
    "            split_clist.append(cur.data)\n",
    "            cur = cur.next\n",
    "        split_clist.append(cur.data)\n",
    "        \n",
    "        self.print_list()\n",
    "        print(\"\\n\")\n",
    "        split_clist.print_list()\n",
    "    \n",
    "    def remove_node(self,node):\n",
    "        if self.head == node:\n",
    "            cur = self.head\n",
    "            while cur.next != self.head:\n",
    "                cur = cur.next\n",
    "            cur.next = self.head.next\n",
    "            self.head = self.head.next\n",
    "        \n",
    "        else:\n",
    "            cur = self.head\n",
    "            prev = None\n",
    "            while cur.next != self.head:\n",
    "                prev = cur\n",
    "                cur = cur.next\n",
    "                if cur == node:\n",
    "                    prev.next = cur.next\n",
    "                    break\n",
    "    \n",
    "    def josephus_circle(self,step):\n",
    "        cur = self.head\n",
    "        while len(self) > 1:\n",
    "            count = 1\n",
    "            while count != step:\n",
    "                cur = cur.next\n",
    "                count += 1\n",
    "            print(\"Node to be removed: \" ,cur.data)\n",
    "            self.remove_node(cur)\n",
    "            cur = cur.next\n",
    "    \n",
    "    def print_list(self):\n",
    "        cur = self.head\n",
    "        while cur:\n",
    "            print(cur.data)\n",
    "            cur = cur.next\n",
    "            if cur == self.head:\n",
    "                break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Node to be removed:  B\n",
      "Node to be removed:  D\n",
      "Node to be removed:  C\n"
     ]
    }
   ],
   "source": [
    "clist = CircularLinkedList()\n",
    "clist.append(\"C\")\n",
    "clist.append(\"D\")\n",
    "clist.prepend(\"B\")\n",
    "clist.prepend(\"A\")\n",
    "clist.josephus_circle(2)\n",
    "# clist.print_list()"
   ]
  }
 ],
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