Design Twitter
<p>Design a simplified version of Twitter where users can post tweets, follow/unfollow another user, and is able to see the <code>10</code> most recent tweets in the user&#39;s news feed.</p>

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

<ul>
	<li><code>Twitter()</code> Initializes your twitter object.</li>
	<li><code>void postTweet(int userId, int tweetId)</code> Composes a new tweet with ID <code>tweetId</code> by the user <code>userId</code>. Each call to this function will be made with a unique <code>tweetId</code>.</li>
	<li><code>List&lt;Integer&gt; getNewsFeed(int userId)</code> Retrieves the <code>10</code> most recent tweet IDs in the user&#39;s news feed. Each item in the news feed must be posted by users who the user followed or by the user themself. Tweets must be <strong>ordered from most recent to least recent</strong>.</li>
	<li><code>void follow(int followerId, int followeeId)</code> The user with ID <code>followerId</code> started following the user with ID <code>followeeId</code>.</li>
	<li><code>void unfollow(int followerId, int followeeId)</code> The user with ID <code>followerId</code> started unfollowing the user with ID <code>followeeId</code>.</li>
</ul>

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

<pre>
<strong>Input</strong>
[&quot;Twitter&quot;, &quot;postTweet&quot;, &quot;getNewsFeed&quot;, &quot;follow&quot;, &quot;postTweet&quot;, &quot;getNewsFeed&quot;, &quot;unfollow&quot;, &quot;getNewsFeed&quot;]
[[], [1, 5], [1], [1, 2], [2, 6], [1], [1, 2], [1]]
<strong>Output</strong>
[null, null, [5], null, null, [6, 5], null, [5]]

<strong>Explanation</strong>
Twitter twitter = new Twitter();
twitter.postTweet(1, 5); // User 1 posts a new tweet (id = 5).
twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 1 tweet id -&gt; [5]. return [5]
twitter.follow(1, 2);    // User 1 follows user 2.
twitter.postTweet(2, 6); // User 2 posts a new tweet (id = 6).
twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 2 tweet ids -&gt; [6, 5]. Tweet id 6 should precede tweet id 5 because it is posted after tweet id 5.
twitter.unfollow(1, 2);  // User 1 unfollows user 2.
twitter.getNewsFeed(1);  // User 1&#39;s news feed should return a list with 1 tweet id -&gt; [5], since user 1 is no longer following user 2.
</pre>

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

<ul>
	<li><code>1 &lt;= userId, followerId, followeeId &lt;= 500</code></li>
	<li><code>0 &lt;= tweetId &lt;= 10<sup>4</sup></code></li>
	<li>All the tweets have <strong>unique</strong> IDs.</li>
	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>postTweet</code>, <code>getNewsFeed</code>, <code>follow</code>, and <code>unfollow</code>.</li>
	<li>A user cannot follow himself.</li>
</ul>

['design-a-file-sharing-system']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "class Twitter {\npublic:\n    Twitter() {\n        \n    }\n    \n    void postTweet(int userId, int tweetId) {\n        \n    }\n    \n    vector<int> getNewsFeed(int userId) {\n        \n    }\n    \n    void follow(int followerId, int followeeId) {\n        \n    }\n    \n    void unfollow(int followerId, int followeeId) {\n        \n    }\n};\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * Twitter* obj = new Twitter();\n * obj->postTweet(userId,tweetId);\n * vector<int> param_2 = obj->getNewsFeed(userId);\n * obj->follow(followerId,followeeId);\n * obj->unfollow(followerId,followeeId);\n */"}, {"value": "java", "text": "Java", "defaultCode": "class Twitter {\n\n    public Twitter() {\n        \n    }\n    \n    public void postTweet(int userId, int tweetId) {\n        \n    }\n    \n    public List<Integer> getNewsFeed(int userId) {\n        \n    }\n    \n    public void follow(int followerId, int followeeId) {\n        \n    }\n    \n    public void unfollow(int followerId, int followeeId) {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * Twitter obj = new Twitter();\n * obj.postTweet(userId,tweetId);\n * List<Integer> param_2 = obj.getNewsFeed(userId);\n * obj.follow(followerId,followeeId);\n * obj.unfollow(followerId,followeeId);\n */"}, {"value": "python", "text": "Python", "defaultCode": "class Twitter(object):\n\n    def __init__(self):\n        \n\n    def postTweet(self, userId, tweetId):\n        \"\"\"\n        :type userId: int\n        :type tweetId: int\n        :rtype: None\n        \"\"\"\n        \n\n    def getNewsFeed(self, userId):\n        \"\"\"\n        :type userId: int\n        :rtype: List[int]\n        \"\"\"\n        \n\n    def follow(self, followerId, followeeId):\n        \"\"\"\n        :type followerId: int\n        :type followeeId: int\n        :rtype: None\n        \"\"\"\n        \n\n    def unfollow(self, followerId, followeeId):\n        \"\"\"\n        :type followerId: int\n        :type followeeId: int\n        :rtype: None\n        \"\"\"\n        \n\n\n# Your Twitter object will be instantiated and called as such:\n# obj = Twitter()\n# obj.postTweet(userId,tweetId)\n# param_2 = obj.getNewsFeed(userId)\n# obj.follow(followerId,followeeId)\n# obj.unfollow(followerId,followeeId)"}, {"value": "python3", "text": "Python3", "defaultCode": "class Twitter:\n\n    def __init__(self):\n        \n\n    def postTweet(self, userId: int, tweetId: int) -> None:\n        \n\n    def getNewsFeed(self, userId: int) -> List[int]:\n        \n\n    def follow(self, followerId: int, followeeId: int) -> None:\n        \n\n    def unfollow(self, followerId: int, followeeId: int) -> None:\n        \n\n\n# Your Twitter object will be instantiated and called as such:\n# obj = Twitter()\n# obj.postTweet(userId,tweetId)\n# param_2 = obj.getNewsFeed(userId)\n# obj.follow(followerId,followeeId)\n# obj.unfollow(followerId,followeeId)"}, {"value": "c", "text": "C", "defaultCode": "\n\n\ntypedef struct {\n    \n} Twitter;\n\n\nTwitter* twitterCreate() {\n    \n}\n\nvoid twitterPostTweet(Twitter* obj, int userId, int tweetId) {\n    \n}\n\nint* twitterGetNewsFeed(Twitter* obj, int userId, int* retSize) {\n    \n}\n\nvoid twitterFollow(Twitter* obj, int followerId, int followeeId) {\n    \n}\n\nvoid twitterUnfollow(Twitter* obj, int followerId, int followeeId) {\n    \n}\n\nvoid twitterFree(Twitter* obj) {\n    \n}\n\n/**\n * Your Twitter struct will be instantiated and called as such:\n * Twitter* obj = twitterCreate();\n * twitterPostTweet(obj, userId, tweetId);\n \n * int* param_2 = twitterGetNewsFeed(obj, userId, retSize);\n \n * twitterFollow(obj, followerId, followeeId);\n \n * twitterUnfollow(obj, followerId, followeeId);\n \n * twitterFree(obj);\n*/"}, {"value": "csharp", "text": "C#", "defaultCode": "public class Twitter {\n\n    public Twitter() {\n        \n    }\n    \n    public void PostTweet(int userId, int tweetId) {\n        \n    }\n    \n    public IList<int> GetNewsFeed(int userId) {\n        \n    }\n    \n    public void Follow(int followerId, int followeeId) {\n        \n    }\n    \n    public void Unfollow(int followerId, int followeeId) {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * Twitter obj = new Twitter();\n * obj.PostTweet(userId,tweetId);\n * IList<int> param_2 = obj.GetNewsFeed(userId);\n * obj.Follow(followerId,followeeId);\n * obj.Unfollow(followerId,followeeId);\n */"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "\nvar Twitter = function() {\n    \n};\n\n/** \n * @param {number} userId \n * @param {number} tweetId\n * @return {void}\n */\nTwitter.prototype.postTweet = function(userId, tweetId) {\n    \n};\n\n/** \n * @param {number} userId\n * @return {number[]}\n */\nTwitter.prototype.getNewsFeed = function(userId) {\n    \n};\n\n/** \n * @param {number} followerId \n * @param {number} followeeId\n * @return {void}\n */\nTwitter.prototype.follow = function(followerId, followeeId) {\n    \n};\n\n/** \n * @param {number} followerId \n * @param {number} followeeId\n * @return {void}\n */\nTwitter.prototype.unfollow = function(followerId, followeeId) {\n    \n};\n\n/** \n * Your Twitter object will be instantiated and called as such:\n * var obj = new Twitter()\n * obj.postTweet(userId,tweetId)\n * var param_2 = obj.getNewsFeed(userId)\n * obj.follow(followerId,followeeId)\n * obj.unfollow(followerId,followeeId)\n */"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "class Twitter {\n    constructor() {\n        \n    }\n\n    postTweet(userId: number, tweetId: number): void {\n        \n    }\n\n    getNewsFeed(userId: number): number[] {\n        \n    }\n\n    follow(followerId: number, followeeId: number): void {\n        \n    }\n\n    unfollow(followerId: number, followeeId: number): void {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * var obj = new Twitter()\n * obj.postTweet(userId,tweetId)\n * var param_2 = obj.getNewsFeed(userId)\n * obj.follow(followerId,followeeId)\n * obj.unfollow(followerId,followeeId)\n */"}, {"value": "php", "text": "PHP", "defaultCode": "class Twitter {\n    /**\n     */\n    function __construct() {\n        \n    }\n  \n    /**\n     * @param Integer $userId\n     * @param Integer $tweetId\n     * @return NULL\n     */\n    function postTweet($userId, $tweetId) {\n        \n    }\n  \n    /**\n     * @param Integer $userId\n     * @return Integer[]\n     */\n    function getNewsFeed($userId) {\n        \n    }\n  \n    /**\n     * @param Integer $followerId\n     * @param Integer $followeeId\n     * @return NULL\n     */\n    function follow($followerId, $followeeId) {\n        \n    }\n  \n    /**\n     * @param Integer $followerId\n     * @param Integer $followeeId\n     * @return NULL\n     */\n    function unfollow($followerId, $followeeId) {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * $obj = Twitter();\n * $obj->postTweet($userId, $tweetId);\n * $ret_2 = $obj->getNewsFeed($userId);\n * $obj->follow($followerId, $followeeId);\n * $obj->unfollow($followerId, $followeeId);\n */"}, {"value": "swift", "text": "Swift", "defaultCode": "\nclass Twitter {\n\n    init() {\n        \n    }\n    \n    func postTweet(_ userId: Int, _ tweetId: Int) {\n        \n    }\n    \n    func getNewsFeed(_ userId: Int) -> [Int] {\n        \n    }\n    \n    func follow(_ followerId: Int, _ followeeId: Int) {\n        \n    }\n    \n    func unfollow(_ followerId: Int, _ followeeId: Int) {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * let obj = Twitter()\n * obj.postTweet(userId, tweetId)\n * let ret_2: [Int] = obj.getNewsFeed(userId)\n * obj.follow(followerId, followeeId)\n * obj.unfollow(followerId, followeeId)\n */"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "class Twitter() {\n\n    fun postTweet(userId: Int, tweetId: Int) {\n        \n    }\n\n    fun getNewsFeed(userId: Int): List<Int> {\n        \n    }\n\n    fun follow(followerId: Int, followeeId: Int) {\n        \n    }\n\n    fun unfollow(followerId: Int, followeeId: Int) {\n        \n    }\n\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * var obj = Twitter()\n * obj.postTweet(userId,tweetId)\n * var param_2 = obj.getNewsFeed(userId)\n * obj.follow(followerId,followeeId)\n * obj.unfollow(followerId,followeeId)\n */"}, {"value": "dart", "text": "Dart", "defaultCode": "class Twitter {\n\n  Twitter() {\n    \n  }\n  \n  void postTweet(int userId, int tweetId) {\n    \n  }\n  \n  List<int> getNewsFeed(int userId) {\n    \n  }\n  \n  void follow(int followerId, int followeeId) {\n    \n  }\n  \n  void unfollow(int followerId, int followeeId) {\n    \n  }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * Twitter obj = Twitter();\n * obj.postTweet(userId,tweetId);\n * List<int> param2 = obj.getNewsFeed(userId);\n * obj.follow(followerId,followeeId);\n * obj.unfollow(followerId,followeeId);\n */"}, {"value": "golang", "text": "Go", "defaultCode": "type Twitter struct {\n    \n}\n\n\nfunc Constructor() Twitter {\n    \n}\n\n\nfunc (this *Twitter) PostTweet(userId int, tweetId int)  {\n    \n}\n\n\nfunc (this *Twitter) GetNewsFeed(userId int) []int {\n    \n}\n\n\nfunc (this *Twitter) Follow(followerId int, followeeId int)  {\n    \n}\n\n\nfunc (this *Twitter) Unfollow(followerId int, followeeId int)  {\n    \n}\n\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * obj := Constructor();\n * obj.PostTweet(userId,tweetId);\n * param_2 := obj.GetNewsFeed(userId);\n * obj.Follow(followerId,followeeId);\n * obj.Unfollow(followerId,followeeId);\n */"}, {"value": "ruby", "text": "Ruby", "defaultCode": "class Twitter\n    def initialize()\n        \n    end\n\n\n=begin\n    :type user_id: Integer\n    :type tweet_id: Integer\n    :rtype: Void\n=end\n    def post_tweet(user_id, tweet_id)\n        \n    end\n\n\n=begin\n    :type user_id: Integer\n    :rtype: Integer[]\n=end\n    def get_news_feed(user_id)\n        \n    end\n\n\n=begin\n    :type follower_id: Integer\n    :type followee_id: Integer\n    :rtype: Void\n=end\n    def follow(follower_id, followee_id)\n        \n    end\n\n\n=begin\n    :type follower_id: Integer\n    :type followee_id: Integer\n    :rtype: Void\n=end\n    def unfollow(follower_id, followee_id)\n        \n    end\n\n\nend\n\n# Your Twitter object will be instantiated and called as such:\n# obj = Twitter.new()\n# obj.post_tweet(user_id, tweet_id)\n# param_2 = obj.get_news_feed(user_id)\n# obj.follow(follower_id, followee_id)\n# obj.unfollow(follower_id, followee_id)"}, {"value": "scala", "text": "Scala", "defaultCode": "class Twitter() {\n\n    def postTweet(userId: Int, tweetId: Int): Unit = {\n        \n    }\n\n    def getNewsFeed(userId: Int): List[Int] = {\n        \n    }\n\n    def follow(followerId: Int, followeeId: Int): Unit = {\n        \n    }\n\n    def unfollow(followerId: Int, followeeId: Int): Unit = {\n        \n    }\n\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * val obj = new Twitter()\n * obj.postTweet(userId,tweetId)\n * val param_2 = obj.getNewsFeed(userId)\n * obj.follow(followerId,followeeId)\n * obj.unfollow(followerId,followeeId)\n */"}, {"value": "rust", "text": "Rust", "defaultCode": "struct Twitter {\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 Twitter {\n\n    fn new() -> Self {\n        \n    }\n    \n    fn post_tweet(&self, user_id: i32, tweet_id: i32) {\n        \n    }\n    \n    fn get_news_feed(&self, user_id: i32) -> Vec<i32> {\n        \n    }\n    \n    fn follow(&self, follower_id: i32, followee_id: i32) {\n        \n    }\n    \n    fn unfollow(&self, follower_id: i32, followee_id: i32) {\n        \n    }\n}\n\n/**\n * Your Twitter object will be instantiated and called as such:\n * let obj = Twitter::new();\n * obj.post_tweet(userId, tweetId);\n * let ret_2: Vec<i32> = obj.get_news_feed(userId);\n * obj.follow(followerId, followeeId);\n * obj.unfollow(followerId, followeeId);\n */"}, {"value": "racket", "text": "Racket", "defaultCode": "(define twitter%\n  (class object%\n    (super-new)\n    \n    (init-field)\n    \n    ; post-tweet : exact-integer? exact-integer? -> void?\n    (define/public (post-tweet user-id tweet-id)\n      )\n    ; get-news-feed : exact-integer? -> (listof exact-integer?)\n    (define/public (get-news-feed user-id)\n      )\n    ; follow : exact-integer? exact-integer? -> void?\n    (define/public (follow follower-id followee-id)\n      )\n    ; unfollow : exact-integer? exact-integer? -> void?\n    (define/public (unfollow follower-id followee-id)\n      )))\n\n;; Your twitter% object will be instantiated and called as such:\n;; (define obj (new twitter%))\n;; (send obj post-tweet user-id tweet-id)\n;; (define param_2 (send obj get-news-feed user-id))\n;; (send obj follow follower-id followee-id)\n;; (send obj unfollow follower-id followee-id)"}, {"value": "erlang", "text": "Erlang", "defaultCode": "-spec twitter_init_() -> any().\ntwitter_init_() ->\n  .\n\n-spec twitter_post_tweet(UserId :: integer(), TweetId :: integer()) -> any().\ntwitter_post_tweet(UserId, TweetId) ->\n  .\n\n-spec twitter_get_news_feed(UserId :: integer()) -> [integer()].\ntwitter_get_news_feed(UserId) ->\n  .\n\n-spec twitter_follow(FollowerId :: integer(), FolloweeId :: integer()) -> any().\ntwitter_follow(FollowerId, FolloweeId) ->\n  .\n\n-spec twitter_unfollow(FollowerId :: integer(), FolloweeId :: integer()) -> any().\ntwitter_unfollow(FollowerId, FolloweeId) ->\n  .\n\n\n%% Your functions will be called as such:\n%% twitter_init_(),\n%% twitter_post_tweet(UserId, TweetId),\n%% Param_2 = twitter_get_news_feed(UserId),\n%% twitter_follow(FollowerId, FolloweeId),\n%% twitter_unfollow(FollowerId, FolloweeId),\n\n%% twitter_init_ will be called before every test case, in which you can do some necessary initializations."}, {"value": "elixir", "text": "Elixir", "defaultCode": "defmodule Twitter do\n  @spec init_() :: any\n  def init_() do\n    \n  end\n\n  @spec post_tweet(user_id :: integer, tweet_id :: integer) :: any\n  def post_tweet(user_id, tweet_id) do\n    \n  end\n\n  @spec get_news_feed(user_id :: integer) :: [integer]\n  def get_news_feed(user_id) do\n    \n  end\n\n  @spec follow(follower_id :: integer, followee_id :: integer) :: any\n  def follow(follower_id, followee_id) do\n    \n  end\n\n  @spec unfollow(follower_id :: integer, followee_id :: integer) :: any\n  def unfollow(follower_id, followee_id) do\n    \n  end\nend\n\n# Your functions will be called as such:\n# Twitter.init_()\n# Twitter.post_tweet(user_id, tweet_id)\n# param_2 = Twitter.get_news_feed(user_id)\n# Twitter.follow(follower_id, followee_id)\n# Twitter.unfollow(follower_id, followee_id)\n\n# Twitter.init_ will be called before every test case, in which you can do some necessary initializations."}]
{
  "classname": "Twitter",
  "constructor": {
    "params": []
  },
  "methods": [
    {
      "params": [
        {
          "type": "integer",
          "name": "userId"
        },
        {
          "type": "integer",
          "name": "tweetId"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "postTweet"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "userId"
        }
      ],
      "return": {
        "type": "list<integer>"
      },
      "name": "getNewsFeed"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "followerId"
        },
        {
          "type": "integer",
          "name": "followeeId"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "follow"
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "followerId"
        },
        {
          "type": "integer",
          "name": "followeeId"
        }
      ],
      "return": {
        "type": "void"
      },
      "name": "unfollow"
    }
  ],
  "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>"]}
['Hash Table', 'Linked List', 'Design', 'Heap (Priority Queue)']