Day09_LEETCODE_142. Linked List Cycle II.ipynb

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      "<__main__.ListNode object at 0x000002B225677FD0>\n"
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    "# Definition for singly-linked list.\n",
    "class ListNode(object):\n",
    "     def __init__(self, x):\n",
    "         self.val = x\n",
    "         self.next = None\n",
    "\n",
    "class Solution(object):\n",
    "    def detectCycle(self, head):\n",
    "        \"\"\"\n",
    "        :type head: ListNode\n",
    "        :rtype: ListNode\n",
    "        \"\"\"\n",
    "        # Initializing an empty hash set\n",
    "        nodespresent= set()\n",
    "        node=head\n",
    "\n",
    "        while node is not None:\n",
    "            if node in nodespresent:\n",
    "                return node    \n",
    "            else:\n",
    "                nodespresent.add(node)  \n",
    "                node=node.next\n",
    "        return None\n",
    "\n",
    "# Creating the linked list [3, 2, 0, -4]\n",
    "node1 = ListNode(3)\n",
    "node2 = ListNode(2)\n",
    "node3 = ListNode(0)\n",
    "node4 = ListNode(-4)\n",
    "\n",
    "node1.next = node2\n",
    "node2.next = node3\n",
    "node3.next = node4\n",
    "node4.next = node2  # Creating a cycle by connecting the last node to the second node\n",
    "    \n",
    "solution = Solution()    \n",
    "result = solution.detectCycle(node1)\n",
    "print(result)"
   ]
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