Copy List with Random Pointer
<p>A linked list of length <code>n</code> is given such that each node contains an additional random pointer, which could point to any node in the list, or <code>null</code>.</p>

<p>Construct a <a href="https://en.wikipedia.org/wiki/Object_copying#Deep_copy" target="_blank"><strong>deep copy</strong></a> of the list. The deep copy should consist of exactly <code>n</code> <strong>brand new</strong> nodes, where each new node has its value set to the value of its corresponding original node. Both the <code>next</code> and <code>random</code> pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. <strong>None of the pointers in the new list should point to nodes in the original list</strong>.</p>

<p>For example, if there are two nodes <code>X</code> and <code>Y</code> in the original list, where <code>X.random --&gt; Y</code>, then for the corresponding two nodes <code>x</code> and <code>y</code> in the copied list, <code>x.random --&gt; y</code>.</p>

<p>Return <em>the head of the copied linked list</em>.</p>

<p>The linked list is represented in the input/output as a list of <code>n</code> nodes. Each node is represented as a pair of <code>[val, random_index]</code> where:</p>

<ul>
	<li><code>val</code>: an integer representing <code>Node.val</code></li>
	<li><code>random_index</code>: the index of the node (range from <code>0</code> to <code>n-1</code>) that the <code>random</code> pointer points to, or <code>null</code> if it does not point to any node.</li>
</ul>

<p>Your code will <strong>only</strong> be given the <code>head</code> of the original linked list.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e1.png" style="width: 700px; height: 142px;" />
<pre>
<strong>Input:</strong> head = [[7,null],[13,0],[11,4],[10,2],[1,0]]
<strong>Output:</strong> [[7,null],[13,0],[11,4],[10,2],[1,0]]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e2.png" style="width: 700px; height: 114px;" />
<pre>
<strong>Input:</strong> head = [[1,1],[2,1]]
<strong>Output:</strong> [[1,1],[2,1]]
</pre>

<p><strong class="example">Example 3:</strong></p>

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/e3.png" style="width: 700px; height: 122px;" /></strong></p>

<pre>
<strong>Input:</strong> head = [[3,null],[3,0],[3,null]]
<strong>Output:</strong> [[3,null],[3,0],[3,null]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= n &lt;= 1000</code></li>
	<li><code>-10<sup>4</sup> &lt;= Node.val &lt;= 10<sup>4</sup></code></li>
	<li><code>Node.random</code> is <code>null</code> or is pointing to some node in the linked list.</li>
</ul>

['clone-graph', 'clone-binary-tree-with-random-pointer', 'clone-n-ary-tree']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "/*\n// Definition for a Node.\nclass Node {\npublic:\n    int val;\n    Node* next;\n    Node* random;\n    \n    Node(int _val) {\n        val = _val;\n        next = NULL;\n        random = NULL;\n    }\n};\n*/\n\nclass Solution {\npublic:\n    Node* copyRandomList(Node* head) {\n        \n    }\n};"}, {"value": "java", "text": "Java", "defaultCode": "/*\n// Definition for a Node.\nclass Node {\n    int val;\n    Node next;\n    Node random;\n\n    public Node(int val) {\n        this.val = val;\n        this.next = null;\n        this.random = null;\n    }\n}\n*/\n\nclass Solution {\n    public Node copyRandomList(Node head) {\n        \n    }\n}"}, {"value": "python", "text": "Python", "defaultCode": "\"\"\"\n# Definition for a Node.\nclass Node:\n    def __init__(self, x, next=None, random=None):\n        self.val = int(x)\n        self.next = next\n        self.random = random\n\"\"\"\n\nclass Solution(object):\n    def copyRandomList(self, head):\n        \"\"\"\n        :type head: Node\n        :rtype: Node\n        \"\"\"\n        "}, {"value": "python3", "text": "Python3", "defaultCode": "\"\"\"\n# Definition for a Node.\nclass Node:\n    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):\n        self.val = int(x)\n        self.next = next\n        self.random = random\n\"\"\"\n\nclass Solution:\n    def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':\n        "}, {"value": "c", "text": "C", "defaultCode": "/**\n * Definition for a Node.\n * struct Node {\n *     int val;\n *     struct Node *next;\n *     struct Node *random;\n * };\n */\n\nstruct Node* copyRandomList(struct Node* head) {\n\t\n}"}, {"value": "csharp", "text": "C#", "defaultCode": "/*\n// Definition for a Node.\npublic class Node {\n    public int val;\n    public Node next;\n    public Node random;\n    \n    public Node(int _val) {\n        val = _val;\n        next = null;\n        random = null;\n    }\n}\n*/\n\npublic class Solution {\n    public Node CopyRandomList(Node head) {\n        \n    }\n}"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "/**\n * // Definition for a _Node.\n * function _Node(val, next, random) {\n *    this.val = val;\n *    this.next = next;\n *    this.random = random;\n * };\n */\n\n/**\n * @param {_Node} head\n * @return {_Node}\n */\nvar copyRandomList = function(head) {\n    \n};"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "/**\n * Definition for _Node.\n * class _Node {\n *     val: number\n *     next: _Node | null\n *     random: _Node | null\n * \n *     constructor(val?: number, next?: _Node, random?: _Node) {\n *         this.val = (val===undefined ? 0 : val)\n *         this.next = (next===undefined ? null : next)\n *         this.random = (random===undefined ? null : random)\n *     }\n * }\n */\n\n\nfunction copyRandomList(head: _Node | null): _Node | null {\n    \n};"}, {"value": "php", "text": "PHP", "defaultCode": "/**\n * Definition for a Node.\n * class Node {\n *     public $val = null;\n *     public $next = null;\n *     public $random = null;\n *     function __construct($val = 0) {\n *         $this->val = $val;\n *         $this->next = null;\n *         $this->random = null;\n *     }\n * }\n */\n\nclass Solution {\n    /**\n     * @param Node $head\n     * @return Node\n     */\n    function copyRandomList($head) {\n        \n    }\n}"}, {"value": "swift", "text": "Swift", "defaultCode": "/**\n * Definition for a Node.\n * public class Node {\n *     public var val: Int\n *     public var next: Node?\n *     public var random: Node?\n *     public init(_ val: Int) {\n *         self.val = val\n *         self.next = nil\n *    \t   self.random = nil\n *     }\n * }\n */\n\nclass Solution {\n    func copyRandomList(_ head: Node?) -> Node? {\n        \n    }\n}"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "/**\n * Example:\n * var ti = Node(5)\n * var v = ti.`val`\n * Definition for a Node.\n * class Node(var `val`: Int) {\n *     var next: Node? = null\n *     var random: Node? = null\n * }\n */\n\nclass Solution {\n    fun copyRandomList(node: Node?): Node? {\n        \n    }\n}"}, {"value": "golang", "text": "Go", "defaultCode": "/**\n * Definition for a Node.\n * type Node struct {\n *     Val int\n *     Next *Node\n *     Random *Node\n * }\n */\n\nfunc copyRandomList(head *Node) *Node {\n    \n}"}, {"value": "ruby", "text": "Ruby", "defaultCode": "# Definition for Node.\n# class Node\n#     attr_accessor :val, :next, :random\n#     def initialize(val = 0)\n#         @val = val\n#\t\t  @next = nil\n#\t\t  @random = nil\n#     end\n# end\n\n# @param {Node} node\n# @return {Node}\ndef copyRandomList(head)\n    \nend"}, {"value": "scala", "text": "Scala", "defaultCode": "/**\n * Definition for a Node.\n * class Node(var _value: Int) {\n *   var value: Int = _value\n *   var next: Node = null\n *   var random: Node = null\n * }\n */\n\nobject Solution {\n    def copyRandomList(head: Node): Node = {\n        \n    }\n}"}]
{
  "name": "copyRandomList",
  "params": [
    {
      "name": "head",
      "type": "ListNode"
    }
  ],
  "return": {
    "type": "ListNode"
  },
  "languages": [
    "cpp",
    "java",
    "python",
    "csharp",
    "javascript",
    "python3",
    "golang",
    "swift",
    "kotlin",
    "ruby",
    "c",
    "scala",
    "php",
    "typescript"
  ],
  "manual": true,
"typescriptCustomType" : "class _Node {\n    val: number\n    next: _Node | null\n    random: _Node | null\n\n    constructor(val?: number, next?: _Node, random?: _Node) {\n        this.val = (val===undefined ? 0 : val)\n        this.next = (next===undefined ? null : next)\n        this.random = (random===undefined ? null : random)\n    }\n}\n"

}
{"cpp": ["C++", "<p>Compiled with <code> clang 19 </code> using the latest C++ 23 standard, and <code>libstdc++</code> provided by GCC 14.</p>\r\n\r\n<p>Your code is compiled with level two optimization (<code>-O2</code>). <a href=\"https://github.com/google/sanitizers/wiki/AddressSanitizer\" target=\"_blank\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\r\n\r\n<p>Most standard library headers are already included automatically for your convenience.</p>"], "java": ["Java", "<p><code>OpenJDK 21</code>. Using compile arguments: <code>--enable-preview --release 21</code></p>\r\n\r\n<p>Most standard library headers are already included automatically for your convenience.</p>\r\n<p>Includes <code>Pair</code> class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.</p>"], "python": ["Python", "<p><code>Python 2.7.18</code>.</p>\r\n\r\n<p>Most libraries are already imported automatically for your convenience, such as <a href=\"https://docs.python.org/2/library/array.html\" target=\"_blank\">array</a>, <a href=\"https://docs.python.org/2/library/bisect.html\" target=\"_blank\">bisect</a>, <a href=\"https://docs.python.org/2/library/collections.html\" target=\"_blank\">collections</a>. If you need more libraries, you can import it yourself.</p>\r\n\r\n<p>For Map/TreeMap data structure, you may use <a href=\"http://www.grantjenks.com/docs/sortedcontainers/\" target=\"_blank\">sortedcontainers</a> library.</p>\r\n\r\n<p>Note that Python 2.7 <a href=\"https://www.python.org/dev/peps/pep-0373/\" target=\"_blank\">is not maintained anymore</a>. For the latest Python, please choose Python3 instead.</p>"], "c": ["C", "<p>Compiled with <code>gcc 14</code> using the gnu11 standard.</p>\r\n\r\n<p>Your code is compiled with level one optimization (<code>-O2</code>). <a href=\"https://github.com/google/sanitizers/wiki/AddressSanitizer\" target=\"_blank\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\r\n\r\n<p>Most standard library headers are already included automatically for your convenience.</p>\r\n\r\n<p>For hash table operations, you may use <a href=\"https://troydhanson.github.io/uthash/\" target=\"_blank\">uthash</a>. \"uthash.h\" is included by default. Below are some examples:</p>\r\n\r\n<p><b>1. Adding an item to a hash.</b>\r\n<pre>\r\nstruct hash_entry {\r\n    int id;            /* we'll use this field as the key */\r\n    char name[10];\r\n    UT_hash_handle hh; /* makes this structure hashable */\r\n};\r\n\r\nstruct hash_entry *users = NULL;\r\n\r\nvoid add_user(struct hash_entry *s) {\r\n    HASH_ADD_INT(users, id, s);\r\n}\r\n</pre>\r\n</p>\r\n\r\n<p><b>2. Looking up an item in a hash:</b>\r\n<pre>\r\nstruct hash_entry *find_user(int user_id) {\r\n    struct hash_entry *s;\r\n    HASH_FIND_INT(users, &user_id, s);\r\n    return s;\r\n}\r\n</pre>\r\n</p>\r\n\r\n<p><b>3. Deleting an item in a hash:</b>\r\n<pre>\r\nvoid delete_user(struct hash_entry *user) {\r\n    HASH_DEL(users, user);  \r\n}\r\n</pre>\r\n</p>"], "csharp": ["C#", "<p><a href=\"https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-13\" target=\"_blank\">C# 13</a> with .NET 9 runtime</p>"], "javascript": ["JavaScript", "<p><code>Node.js 22.14.0</code>.</p>\r\n\r\n<p>Your code is run with <code>--harmony</code> flag, enabling <a href=\"http://node.green/\" target=\"_blank\">new ES6 features</a>.</p>\r\n\r\n<p><a href=\"https://lodash.com\" target=\"_blank\">lodash.js</a> library is included by default.</p>\r\n\r\n<p>For Priority Queue / Queue data structures, you may use 6.3.2 version of <a href=\"https://github.com/datastructures-js/priority-queue/tree/v6.3.2\" target=\"_blank\">datastructures-js/priority-queue</a> and 4.2.3 version of <a href=\"https://github.com/datastructures-js/queue/tree/v4.2.3\" target=\"_blank\">datastructures-js/queue</a> and 1.0.4 version of <a href=\"https://github.com/datastructures-js/deque/tree/v1.0.4\" target=\"_blank\">datastructures-js/deque</a>.</p>"], "ruby": ["Ruby", "<p><code>Ruby 3.2</code></p>\r\n\r\n<p>Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms</p>"], "swift": ["Swift", "<p><code>Swift 6.0</code>.</p>\r\n\r\n<p>You may use the following packages:<br/>\r\n<a href=\"https://github.com/apple/swift-algorithms/tree/1.2.0\" target=\"_blank\">swift-algorithms 1.2.0</a><br/>\r\n<a href=\"https://github.com/apple/swift-collections/tree/1.1.4\" target=\"_blank\">swift-collections 1.1.4</a><br/>\r\n<a href=\"https://github.com/apple/swift-numerics/tree/1.0.2\" target=\"_blank\">swift-numerics 1.0.2</a></p>"], "golang": ["Go", "<p><code>Go 1.23</code></p>\r\n<p>Support <a href=\"https://pkg.go.dev/github.com/emirpasic/gods@v1.18.1\" target=\"_blank\">https://pkg.go.dev/github.com/emirpasic/gods@v1.18.1</a> and <a href=\"https://pkg.go.dev/github.com/emirpasic/gods/v2@v2.0.0-alpha\" target=\"_blank\">https://pkg.go.dev/github.com/emirpasic/gods/v2@v2.0.0-alpha</a> library.</p>"], "python3": ["Python3", "<p><code>Python 3.11</code>.</p>\r\n\r\n<p>Most libraries are already imported automatically for your convenience, such as <a href=\"https://docs.python.org/3/library/array.html\" target=\"_blank\">array</a>, <a href=\"https://docs.python.org/3/library/bisect.html\" target=\"_blank\">bisect</a>, <a href=\"https://docs.python.org/3/library/collections.html\" target=\"_blank\">collections</a>. If you need more libraries, you can import it yourself.</p>\r\n\r\n<p>For Map/TreeMap data structure, you may use <a href=\"http://www.grantjenks.com/docs/sortedcontainers/\" target=\"_blank\">sortedcontainers</a> library.</p>"], "scala": ["Scala", "<p><code>Scala 3.3.1</code>.</p>"], "kotlin": ["Kotlin", "<p><code>Kotlin 2.1.10</code>.</p>"], "php": ["PHP", "<p><code>PHP 8.2</code>.</p>\r\n<p>With bcmath module</p>"], "typescript": ["Typescript", "<p><code>TypeScript 5.7.3, Node.js 22.14.0</code>.</p>\r\n\r\n<p>Compile Options: <code>--alwaysStrict --strictBindCallApply --strictFunctionTypes --target ES2024</code></p>\r\n\r\n<p><a href=\"https://lodash.com\" target=\"_blank\">lodash.js</a> library is included by default.</p>\r\n\r\n<p>For Priority Queue / Queue data structures, you may use 6.3.2 version of <a href=\"https://github.com/datastructures-js/priority-queue/tree/v6.3.2\" target=\"_blank\">datastructures-js/priority-queue</a> and 4.2.3 version of <a href=\"https://github.com/datastructures-js/queue/tree/v4.2.3\" target=\"_blank\">datastructures-js/queue</a> and 1.0.4 version of <a href=\"https://github.com/datastructures-js/deque/tree/v1.0.4\" target=\"_blank\">datastructures-js/deque</a>.</p>"]}
['Hash Table', 'Linked List']