Design Linked List
<p>Design your implementation of the linked list. You can choose to use a singly or doubly linked list.<br />
A node in a singly linked list should have two attributes: <code>val</code> and <code>next</code>. <code>val</code> is the value of the current node, and <code>next</code> is a pointer/reference to the next node.<br />
If you want to use the doubly linked list, you will need one more attribute <code>prev</code> to indicate the previous node in the linked list. Assume all nodes in the linked list are <strong>0-indexed</strong>.</p>

<p>Implement the <code>MyLinkedList</code> class:</p>

<ul>
	<li><code>MyLinkedList()</code> Initializes the <code>MyLinkedList</code> object.</li>
	<li><code>int get(int index)</code> Get the value of the <code>index<sup>th</sup></code> node in the linked list. If the index is invalid, return <code>-1</code>.</li>
	<li><code>void addAtHead(int val)</code> Add a node of value <code>val</code> before the first element of the linked list. After the insertion, the new node will be the first node of the linked list.</li>
	<li><code>void addAtTail(int val)</code> Append a node of value <code>val</code> as the last element of the linked list.</li>
	<li><code>void addAtIndex(int index, int val)</code> Add a node of value <code>val</code> before the <code>index<sup>th</sup></code> node in the linked list. If <code>index</code> equals the length of the linked list, the node will be appended to the end of the linked list. If <code>index</code> is greater than the length, the node <strong>will not be inserted</strong>.</li>
	<li><code>void deleteAtIndex(int index)</code> Delete the <code>index<sup>th</sup></code> node in the linked list, if the index is valid.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input</strong>
[&quot;MyLinkedList&quot;, &quot;addAtHead&quot;, &quot;addAtTail&quot;, &quot;addAtIndex&quot;, &quot;get&quot;, &quot;deleteAtIndex&quot;, &quot;get&quot;]
[[], [1], [3], [1, 2], [1], [1], [1]]
<strong>Output</strong>
[null, null, null, null, 2, null, 3]

<strong>Explanation</strong>
MyLinkedList myLinkedList = new MyLinkedList();
myLinkedList.addAtHead(1);
myLinkedList.addAtTail(3);
myLinkedList.addAtIndex(1, 2);    // linked list becomes 1-&gt;2-&gt;3
myLinkedList.get(1);              // return 2
myLinkedList.deleteAtIndex(1);    // now the linked list is 1-&gt;3
myLinkedList.get(1);              // return 3
</pre>

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

<ul>
	<li><code>0 &lt;= index, val &lt;= 1000</code></li>
	<li>Please do not use the built-in LinkedList library.</li>
	<li>At most <code>2000</code> calls will be made to <code>get</code>, <code>addAtHead</code>, <code>addAtTail</code>, <code>addAtIndex</code> and <code>deleteAtIndex</code>.</li>
</ul>

['design-skiplist']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "class MyLinkedList {\npublic:\n    MyLinkedList() {\n        \n    }\n    \n    int get(int index) {\n        \n    }\n    \n    void addAtHead(int val) {\n        \n    }\n    \n    void addAtTail(int val) {\n        \n    }\n    \n    void addAtIndex(int index, int val) {\n        \n    }\n    \n    void deleteAtIndex(int index) {\n        \n    }\n};\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * MyLinkedList* obj = new MyLinkedList();\n * int param_1 = obj->get(index);\n * obj->addAtHead(val);\n * obj->addAtTail(val);\n * obj->addAtIndex(index,val);\n * obj->deleteAtIndex(index);\n */"}, {"value": "java", "text": "Java", "defaultCode": "class MyLinkedList {\n\n    public MyLinkedList() {\n        \n    }\n    \n    public int get(int index) {\n        \n    }\n    \n    public void addAtHead(int val) {\n        \n    }\n    \n    public void addAtTail(int val) {\n        \n    }\n    \n    public void addAtIndex(int index, int val) {\n        \n    }\n    \n    public void deleteAtIndex(int index) {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * MyLinkedList obj = new MyLinkedList();\n * int param_1 = obj.get(index);\n * obj.addAtHead(val);\n * obj.addAtTail(val);\n * obj.addAtIndex(index,val);\n * obj.deleteAtIndex(index);\n */"}, {"value": "python", "text": "Python", "defaultCode": "class MyLinkedList(object):\n\n    def __init__(self):\n        \n\n    def get(self, index):\n        \"\"\"\n        :type index: int\n        :rtype: int\n        \"\"\"\n        \n\n    def addAtHead(self, val):\n        \"\"\"\n        :type val: int\n        :rtype: None\n        \"\"\"\n        \n\n    def addAtTail(self, val):\n        \"\"\"\n        :type val: int\n        :rtype: None\n        \"\"\"\n        \n\n    def addAtIndex(self, index, val):\n        \"\"\"\n        :type index: int\n        :type val: int\n        :rtype: None\n        \"\"\"\n        \n\n    def deleteAtIndex(self, index):\n        \"\"\"\n        :type index: int\n        :rtype: None\n        \"\"\"\n        \n\n\n# Your MyLinkedList object will be instantiated and called as such:\n# obj = MyLinkedList()\n# param_1 = obj.get(index)\n# obj.addAtHead(val)\n# obj.addAtTail(val)\n# obj.addAtIndex(index,val)\n# obj.deleteAtIndex(index)"}, {"value": "python3", "text": "Python3", "defaultCode": "class MyLinkedList:\n\n    def __init__(self):\n        \n\n    def get(self, index: int) -> int:\n        \n\n    def addAtHead(self, val: int) -> None:\n        \n\n    def addAtTail(self, val: int) -> None:\n        \n\n    def addAtIndex(self, index: int, val: int) -> None:\n        \n\n    def deleteAtIndex(self, index: int) -> None:\n        \n\n\n# Your MyLinkedList object will be instantiated and called as such:\n# obj = MyLinkedList()\n# param_1 = obj.get(index)\n# obj.addAtHead(val)\n# obj.addAtTail(val)\n# obj.addAtIndex(index,val)\n# obj.deleteAtIndex(index)"}, {"value": "c", "text": "C", "defaultCode": "\n\n\ntypedef struct {\n    \n} MyLinkedList;\n\n\nMyLinkedList* myLinkedListCreate() {\n    \n}\n\nint myLinkedListGet(MyLinkedList* obj, int index) {\n    \n}\n\nvoid myLinkedListAddAtHead(MyLinkedList* obj, int val) {\n    \n}\n\nvoid myLinkedListAddAtTail(MyLinkedList* obj, int val) {\n    \n}\n\nvoid myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val) {\n    \n}\n\nvoid myLinkedListDeleteAtIndex(MyLinkedList* obj, int index) {\n    \n}\n\nvoid myLinkedListFree(MyLinkedList* obj) {\n    \n}\n\n/**\n * Your MyLinkedList struct will be instantiated and called as such:\n * MyLinkedList* obj = myLinkedListCreate();\n * int param_1 = myLinkedListGet(obj, index);\n \n * myLinkedListAddAtHead(obj, val);\n \n * myLinkedListAddAtTail(obj, val);\n \n * myLinkedListAddAtIndex(obj, index, val);\n \n * myLinkedListDeleteAtIndex(obj, index);\n \n * myLinkedListFree(obj);\n*/"}, {"value": "csharp", "text": "C#", "defaultCode": "public class MyLinkedList {\n\n    public MyLinkedList() {\n        \n    }\n    \n    public int Get(int index) {\n        \n    }\n    \n    public void AddAtHead(int val) {\n        \n    }\n    \n    public void AddAtTail(int val) {\n        \n    }\n    \n    public void AddAtIndex(int index, int val) {\n        \n    }\n    \n    public void DeleteAtIndex(int index) {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * MyLinkedList obj = new MyLinkedList();\n * int param_1 = obj.Get(index);\n * obj.AddAtHead(val);\n * obj.AddAtTail(val);\n * obj.AddAtIndex(index,val);\n * obj.DeleteAtIndex(index);\n */"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "\nvar MyLinkedList = function() {\n    \n};\n\n/** \n * @param {number} index\n * @return {number}\n */\nMyLinkedList.prototype.get = function(index) {\n    \n};\n\n/** \n * @param {number} val\n * @return {void}\n */\nMyLinkedList.prototype.addAtHead = function(val) {\n    \n};\n\n/** \n * @param {number} val\n * @return {void}\n */\nMyLinkedList.prototype.addAtTail = function(val) {\n    \n};\n\n/** \n * @param {number} index \n * @param {number} val\n * @return {void}\n */\nMyLinkedList.prototype.addAtIndex = function(index, val) {\n    \n};\n\n/** \n * @param {number} index\n * @return {void}\n */\nMyLinkedList.prototype.deleteAtIndex = function(index) {\n    \n};\n\n/** \n * Your MyLinkedList object will be instantiated and called as such:\n * var obj = new MyLinkedList()\n * var param_1 = obj.get(index)\n * obj.addAtHead(val)\n * obj.addAtTail(val)\n * obj.addAtIndex(index,val)\n * obj.deleteAtIndex(index)\n */"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "class MyLinkedList {\n    constructor() {\n        \n    }\n\n    get(index: number): number {\n        \n    }\n\n    addAtHead(val: number): void {\n        \n    }\n\n    addAtTail(val: number): void {\n        \n    }\n\n    addAtIndex(index: number, val: number): void {\n        \n    }\n\n    deleteAtIndex(index: number): void {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * var obj = new MyLinkedList()\n * var param_1 = obj.get(index)\n * obj.addAtHead(val)\n * obj.addAtTail(val)\n * obj.addAtIndex(index,val)\n * obj.deleteAtIndex(index)\n */"}, {"value": "php", "text": "PHP", "defaultCode": "class MyLinkedList {\n    /**\n     */\n    function __construct() {\n        \n    }\n  \n    /**\n     * @param Integer $index\n     * @return Integer\n     */\n    function get($index) {\n        \n    }\n  \n    /**\n     * @param Integer $val\n     * @return NULL\n     */\n    function addAtHead($val) {\n        \n    }\n  \n    /**\n     * @param Integer $val\n     * @return NULL\n     */\n    function addAtTail($val) {\n        \n    }\n  \n    /**\n     * @param Integer $index\n     * @param Integer $val\n     * @return NULL\n     */\n    function addAtIndex($index, $val) {\n        \n    }\n  \n    /**\n     * @param Integer $index\n     * @return NULL\n     */\n    function deleteAtIndex($index) {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * $obj = MyLinkedList();\n * $ret_1 = $obj->get($index);\n * $obj->addAtHead($val);\n * $obj->addAtTail($val);\n * $obj->addAtIndex($index, $val);\n * $obj->deleteAtIndex($index);\n */"}, {"value": "swift", "text": "Swift", "defaultCode": "\nclass MyLinkedList {\n\n    init() {\n        \n    }\n    \n    func get(_ index: Int) -> Int {\n        \n    }\n    \n    func addAtHead(_ val: Int) {\n        \n    }\n    \n    func addAtTail(_ val: Int) {\n        \n    }\n    \n    func addAtIndex(_ index: Int, _ val: Int) {\n        \n    }\n    \n    func deleteAtIndex(_ index: Int) {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * let obj = MyLinkedList()\n * let ret_1: Int = obj.get(index)\n * obj.addAtHead(val)\n * obj.addAtTail(val)\n * obj.addAtIndex(index, val)\n * obj.deleteAtIndex(index)\n */"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "class MyLinkedList() {\n\n    fun get(index: Int): Int {\n        \n    }\n\n    fun addAtHead(`val`: Int) {\n        \n    }\n\n    fun addAtTail(`val`: Int) {\n        \n    }\n\n    fun addAtIndex(index: Int, `val`: Int) {\n        \n    }\n\n    fun deleteAtIndex(index: Int) {\n        \n    }\n\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * var obj = MyLinkedList()\n * var param_1 = obj.get(index)\n * obj.addAtHead(`val`)\n * obj.addAtTail(`val`)\n * obj.addAtIndex(index,`val`)\n * obj.deleteAtIndex(index)\n */"}, {"value": "dart", "text": "Dart", "defaultCode": "class MyLinkedList {\n\n  MyLinkedList() {\n    \n  }\n  \n  int get(int index) {\n    \n  }\n  \n  void addAtHead(int val) {\n    \n  }\n  \n  void addAtTail(int val) {\n    \n  }\n  \n  void addAtIndex(int index, int val) {\n    \n  }\n  \n  void deleteAtIndex(int index) {\n    \n  }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * MyLinkedList obj = MyLinkedList();\n * int param1 = obj.get(index);\n * obj.addAtHead(val);\n * obj.addAtTail(val);\n * obj.addAtIndex(index,val);\n * obj.deleteAtIndex(index);\n */"}, {"value": "golang", "text": "Go", "defaultCode": "type MyLinkedList struct {\n    \n}\n\n\nfunc Constructor() MyLinkedList {\n    \n}\n\n\nfunc (this *MyLinkedList) Get(index int) int {\n    \n}\n\n\nfunc (this *MyLinkedList) AddAtHead(val int)  {\n    \n}\n\n\nfunc (this *MyLinkedList) AddAtTail(val int)  {\n    \n}\n\n\nfunc (this *MyLinkedList) AddAtIndex(index int, val int)  {\n    \n}\n\n\nfunc (this *MyLinkedList) DeleteAtIndex(index int)  {\n    \n}\n\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * obj := Constructor();\n * param_1 := obj.Get(index);\n * obj.AddAtHead(val);\n * obj.AddAtTail(val);\n * obj.AddAtIndex(index,val);\n * obj.DeleteAtIndex(index);\n */"}, {"value": "ruby", "text": "Ruby", "defaultCode": "class MyLinkedList\n    def initialize()\n        \n    end\n\n\n=begin\n    :type index: Integer\n    :rtype: Integer\n=end\n    def get(index)\n        \n    end\n\n\n=begin\n    :type val: Integer\n    :rtype: Void\n=end\n    def add_at_head(val)\n        \n    end\n\n\n=begin\n    :type val: Integer\n    :rtype: Void\n=end\n    def add_at_tail(val)\n        \n    end\n\n\n=begin\n    :type index: Integer\n    :type val: Integer\n    :rtype: Void\n=end\n    def add_at_index(index, val)\n        \n    end\n\n\n=begin\n    :type index: Integer\n    :rtype: Void\n=end\n    def delete_at_index(index)\n        \n    end\n\n\nend\n\n# Your MyLinkedList object will be instantiated and called as such:\n# obj = MyLinkedList.new()\n# param_1 = obj.get(index)\n# obj.add_at_head(val)\n# obj.add_at_tail(val)\n# obj.add_at_index(index, val)\n# obj.delete_at_index(index)"}, {"value": "scala", "text": "Scala", "defaultCode": "class MyLinkedList() {\n\n    def get(index: Int): Int = {\n        \n    }\n\n    def addAtHead(`val`: Int): Unit = {\n        \n    }\n\n    def addAtTail(`val`: Int): Unit = {\n        \n    }\n\n    def addAtIndex(index: Int, `val`: Int): Unit = {\n        \n    }\n\n    def deleteAtIndex(index: Int): Unit = {\n        \n    }\n\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * val obj = new MyLinkedList()\n * val param_1 = obj.get(index)\n * obj.addAtHead(`val`)\n * obj.addAtTail(`val`)\n * obj.addAtIndex(index,`val`)\n * obj.deleteAtIndex(index)\n */"}, {"value": "rust", "text": "Rust", "defaultCode": "struct MyLinkedList {\n\n}\n\n\n/** \n * `&self` means the method takes an immutable reference.\n * If you need a mutable reference, change it to `&mut self` instead.\n */\nimpl MyLinkedList {\n\n    fn new() -> Self {\n        \n    }\n    \n    fn get(&self, index: i32) -> i32 {\n        \n    }\n    \n    fn add_at_head(&self, val: i32) {\n        \n    }\n    \n    fn add_at_tail(&self, val: i32) {\n        \n    }\n    \n    fn add_at_index(&self, index: i32, val: i32) {\n        \n    }\n    \n    fn delete_at_index(&self, index: i32) {\n        \n    }\n}\n\n/**\n * Your MyLinkedList object will be instantiated and called as such:\n * let obj = MyLinkedList::new();\n * let ret_1: i32 = obj.get(index);\n * obj.add_at_head(val);\n * obj.add_at_tail(val);\n * obj.add_at_index(index, val);\n * obj.delete_at_index(index);\n */"}, {"value": "racket", "text": "Racket", "defaultCode": "(define my-linked-list%\n  (class object%\n    (super-new)\n    \n    (init-field)\n    \n    ; get : exact-integer? -> exact-integer?\n    (define/public (get index)\n      )\n    ; add-at-head : exact-integer? -> void?\n    (define/public (add-at-head val)\n      )\n    ; add-at-tail : exact-integer? -> void?\n    (define/public (add-at-tail val)\n      )\n    ; add-at-index : exact-integer? exact-integer? -> void?\n    (define/public (add-at-index index val)\n      )\n    ; delete-at-index : exact-integer? -> void?\n    (define/public (delete-at-index index)\n      )))\n\n;; Your my-linked-list% object will be instantiated and called as such:\n;; (define obj (new my-linked-list%))\n;; (define param_1 (send obj get index))\n;; (send obj add-at-head val)\n;; (send obj add-at-tail val)\n;; (send obj add-at-index index val)\n;; (send obj delete-at-index index)"}, {"value": "erlang", "text": "Erlang", "defaultCode": "-spec my_linked_list_init_() -> any().\nmy_linked_list_init_() ->\n  .\n\n-spec my_linked_list_get(Index :: integer()) -> integer().\nmy_linked_list_get(Index) ->\n  .\n\n-spec my_linked_list_add_at_head(Val :: integer()) -> any().\nmy_linked_list_add_at_head(Val) ->\n  .\n\n-spec my_linked_list_add_at_tail(Val :: integer()) -> any().\nmy_linked_list_add_at_tail(Val) ->\n  .\n\n-spec my_linked_list_add_at_index(Index :: integer(), Val :: integer()) -> any().\nmy_linked_list_add_at_index(Index, Val) ->\n  .\n\n-spec my_linked_list_delete_at_index(Index :: integer()) -> any().\nmy_linked_list_delete_at_index(Index) ->\n  .\n\n\n%% Your functions will be called as such:\n%% my_linked_list_init_(),\n%% Param_1 = my_linked_list_get(Index),\n%% my_linked_list_add_at_head(Val),\n%% my_linked_list_add_at_tail(Val),\n%% my_linked_list_add_at_index(Index, Val),\n%% my_linked_list_delete_at_index(Index),\n\n%% my_linked_list_init_ will be called before every test case, in which you can do some necessary initializations."}, {"value": "elixir", "text": "Elixir", "defaultCode": "defmodule MyLinkedList do\n  @spec init_() :: any\n  def init_() do\n    \n  end\n\n  @spec get(index :: integer) :: integer\n  def get(index) do\n    \n  end\n\n  @spec add_at_head(val :: integer) :: any\n  def add_at_head(val) do\n    \n  end\n\n  @spec add_at_tail(val :: integer) :: any\n  def add_at_tail(val) do\n    \n  end\n\n  @spec add_at_index(index :: integer, val :: integer) :: any\n  def add_at_index(index, val) do\n    \n  end\n\n  @spec delete_at_index(index :: integer) :: any\n  def delete_at_index(index) do\n    \n  end\nend\n\n# Your functions will be called as such:\n# MyLinkedList.init_()\n# param_1 = MyLinkedList.get(index)\n# MyLinkedList.add_at_head(val)\n# MyLinkedList.add_at_tail(val)\n# MyLinkedList.add_at_index(index, val)\n# MyLinkedList.delete_at_index(index)\n\n# MyLinkedList.init_ will be called before every test case, in which you can do some necessary initializations."}]
{
  "classname": "MyLinkedList",
  "constructor": {
    "params": []
  },
  "methods": [
    {
      "params": [
        {
          "type": "integer",
          "name": "index"
        }
      ],
      "return": {
        "type": "integer"
      },
      "name": "get"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "val"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "addAtHead"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "val"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "addAtTail"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "index"
        },
        {
          "type": "integer",
          "name": "val"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "addAtIndex"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "index"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "deleteAtIndex"
    }
  ],
  "return": {
    "type": "boolean"
  },
  "systemdesign": true
}
{"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>"], "rust": ["Rust", "<p><code>Rust 1.85.0</code>. Your code will be compiled with <code>opt-level</code> 2.</p>\r\n\r\n<p>Supports <a href=\"https://crates.io/crates/rand\" target=\"_blank\">rand v0.8</a> and <a href=\"https://crates.io/crates/regex\" target=\"_blank\">regex\u00a0v1</a> and <a href=\"https://crates.io/crates/itertools\" target=\"_blank\">itertools\u00a0v0.14</a> from crates.io</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>"], "racket": ["Racket", "<p><a href=\"https://docs.racket-lang.org/guide/performance.html#%28tech._c%29\" target=\"_blank\">Racket CS</a> v8.15</p>\r\n\r\n<p>Using <code>#lang racket</code></p>\r\n\r\n<p>Required <code>data/gvector data/queue data/order data/heap</code> automatically for your convenience</p>"], "erlang": ["Erlang", "Erlang/OTP 26"], "elixir": ["Elixir", "Elixir 1.17 with Erlang/OTP 26"], "dart": ["Dart", "<p>Dart 3.2. You may use package <a href=\"https://pub.dev/packages/collection/versions/1.18.0\" target=\"_blank\">collection</a></p>\r\n\r\n<p>Your code will be run directly without compiling</p>"]}
['Linked List', 'Design']