Find Median from Data Stream
<p>The <strong>median</strong> is the middle value in an ordered integer list. If the size of the list is even, there is no middle value, and the median is the mean of the two middle values.</p>

<ul>
	<li>For example, for <code>arr = [2,3,4]</code>, the median is <code>3</code>.</li>
	<li>For example, for <code>arr = [2,3]</code>, the median is <code>(2 + 3) / 2 = 2.5</code>.</li>
</ul>

<p>Implement the MedianFinder class:</p>

<ul>
	<li><code>MedianFinder()</code> initializes the <code>MedianFinder</code> object.</li>
	<li><code>void addNum(int num)</code> adds the integer <code>num</code> from the data stream to the data structure.</li>
	<li><code>double findMedian()</code> returns the median of all elements so far. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</li>
</ul>

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

<pre>
<strong>Input</strong>
[&quot;MedianFinder&quot;, &quot;addNum&quot;, &quot;addNum&quot;, &quot;findMedian&quot;, &quot;addNum&quot;, &quot;findMedian&quot;]
[[], [1], [2], [], [3], []]
<strong>Output</strong>
[null, null, null, 1.5, null, 2.0]

<strong>Explanation</strong>
MedianFinder medianFinder = new MedianFinder();
medianFinder.addNum(1);    // arr = [1]
medianFinder.addNum(2);    // arr = [1, 2]
medianFinder.findMedian(); // return 1.5 (i.e., (1 + 2) / 2)
medianFinder.addNum(3);    // arr[1, 2, 3]
medianFinder.findMedian(); // return 2.0
</pre>

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

<ul>
	<li><code>-10<sup>5</sup> &lt;= num &lt;= 10<sup>5</sup></code></li>
	<li>There will be at least one element in the data structure before calling <code>findMedian</code>.</li>
	<li>At most <code>5 * 10<sup>4</sup></code> calls will be made to <code>addNum</code> and <code>findMedian</code>.</li>
</ul>

<p>&nbsp;</p>
<p><strong>Follow up:</strong></p>

<ul>
	<li>If all integer numbers from the stream are in the range <code>[0, 100]</code>, how would you optimize your solution?</li>
	<li>If <code>99%</code> of all integer numbers from the stream are in the range <code>[0, 100]</code>, how would you optimize your solution?</li>
</ul>

['sliding-window-median', 'finding-mk-average', 'sequentially-ordinal-rank-tracker', 'minimum-operations-to-make-median-of-array-equal-to-k', 'minimum-operations-to-make-subarray-elements-equal', 'minimum-operations-to-make-elements-within-k-subarrays-equal']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "class MedianFinder {\npublic:\n    MedianFinder() {\n        \n    }\n    \n    void addNum(int num) {\n        \n    }\n    \n    double findMedian() {\n        \n    }\n};\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * MedianFinder* obj = new MedianFinder();\n * obj->addNum(num);\n * double param_2 = obj->findMedian();\n */"}, {"value": "java", "text": "Java", "defaultCode": "class MedianFinder {\n\n    public MedianFinder() {\n        \n    }\n    \n    public void addNum(int num) {\n        \n    }\n    \n    public double findMedian() {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * MedianFinder obj = new MedianFinder();\n * obj.addNum(num);\n * double param_2 = obj.findMedian();\n */"}, {"value": "python", "text": "Python", "defaultCode": "class MedianFinder(object):\n\n    def __init__(self):\n        \n\n    def addNum(self, num):\n        \"\"\"\n        :type num: int\n        :rtype: None\n        \"\"\"\n        \n\n    def findMedian(self):\n        \"\"\"\n        :rtype: float\n        \"\"\"\n        \n\n\n# Your MedianFinder object will be instantiated and called as such:\n# obj = MedianFinder()\n# obj.addNum(num)\n# param_2 = obj.findMedian()"}, {"value": "python3", "text": "Python3", "defaultCode": "class MedianFinder:\n\n    def __init__(self):\n        \n\n    def addNum(self, num: int) -> None:\n        \n\n    def findMedian(self) -> float:\n        \n\n\n# Your MedianFinder object will be instantiated and called as such:\n# obj = MedianFinder()\n# obj.addNum(num)\n# param_2 = obj.findMedian()"}, {"value": "c", "text": "C", "defaultCode": "\n\n\ntypedef struct {\n    \n} MedianFinder;\n\n\nMedianFinder* medianFinderCreate() {\n    \n}\n\nvoid medianFinderAddNum(MedianFinder* obj, int num) {\n    \n}\n\ndouble medianFinderFindMedian(MedianFinder* obj) {\n    \n}\n\nvoid medianFinderFree(MedianFinder* obj) {\n    \n}\n\n/**\n * Your MedianFinder struct will be instantiated and called as such:\n * MedianFinder* obj = medianFinderCreate();\n * medianFinderAddNum(obj, num);\n \n * double param_2 = medianFinderFindMedian(obj);\n \n * medianFinderFree(obj);\n*/"}, {"value": "csharp", "text": "C#", "defaultCode": "public class MedianFinder {\n\n    public MedianFinder() {\n        \n    }\n    \n    public void AddNum(int num) {\n        \n    }\n    \n    public double FindMedian() {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * MedianFinder obj = new MedianFinder();\n * obj.AddNum(num);\n * double param_2 = obj.FindMedian();\n */"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "\nvar MedianFinder = function() {\n    \n};\n\n/** \n * @param {number} num\n * @return {void}\n */\nMedianFinder.prototype.addNum = function(num) {\n    \n};\n\n/**\n * @return {number}\n */\nMedianFinder.prototype.findMedian = function() {\n    \n};\n\n/** \n * Your MedianFinder object will be instantiated and called as such:\n * var obj = new MedianFinder()\n * obj.addNum(num)\n * var param_2 = obj.findMedian()\n */"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "class MedianFinder {\n    constructor() {\n        \n    }\n\n    addNum(num: number): void {\n        \n    }\n\n    findMedian(): number {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * var obj = new MedianFinder()\n * obj.addNum(num)\n * var param_2 = obj.findMedian()\n */"}, {"value": "php", "text": "PHP", "defaultCode": "class MedianFinder {\n    /**\n     */\n    function __construct() {\n        \n    }\n  \n    /**\n     * @param Integer $num\n     * @return NULL\n     */\n    function addNum($num) {\n        \n    }\n  \n    /**\n     * @return Float\n     */\n    function findMedian() {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * $obj = MedianFinder();\n * $obj->addNum($num);\n * $ret_2 = $obj->findMedian();\n */"}, {"value": "swift", "text": "Swift", "defaultCode": "\nclass MedianFinder {\n\n    init() {\n        \n    }\n    \n    func addNum(_ num: Int) {\n        \n    }\n    \n    func findMedian() -> Double {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * let obj = MedianFinder()\n * obj.addNum(num)\n * let ret_2: Double = obj.findMedian()\n */"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "class MedianFinder() {\n\n    fun addNum(num: Int) {\n        \n    }\n\n    fun findMedian(): Double {\n        \n    }\n\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * var obj = MedianFinder()\n * obj.addNum(num)\n * var param_2 = obj.findMedian()\n */"}, {"value": "dart", "text": "Dart", "defaultCode": "class MedianFinder {\n\n  MedianFinder() {\n    \n  }\n  \n  void addNum(int num) {\n    \n  }\n  \n  double findMedian() {\n    \n  }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * MedianFinder obj = MedianFinder();\n * obj.addNum(num);\n * double param2 = obj.findMedian();\n */"}, {"value": "golang", "text": "Go", "defaultCode": "type MedianFinder struct {\n    \n}\n\n\nfunc Constructor() MedianFinder {\n    \n}\n\n\nfunc (this *MedianFinder) AddNum(num int)  {\n    \n}\n\n\nfunc (this *MedianFinder) FindMedian() float64 {\n    \n}\n\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * obj := Constructor();\n * obj.AddNum(num);\n * param_2 := obj.FindMedian();\n */"}, {"value": "ruby", "text": "Ruby", "defaultCode": "class MedianFinder\n    def initialize()\n        \n    end\n\n\n=begin\n    :type num: Integer\n    :rtype: Void\n=end\n    def add_num(num)\n        \n    end\n\n\n=begin\n    :rtype: Float\n=end\n    def find_median()\n        \n    end\n\n\nend\n\n# Your MedianFinder object will be instantiated and called as such:\n# obj = MedianFinder.new()\n# obj.add_num(num)\n# param_2 = obj.find_median()"}, {"value": "scala", "text": "Scala", "defaultCode": "class MedianFinder() {\n\n    def addNum(num: Int): Unit = {\n        \n    }\n\n    def findMedian(): Double = {\n        \n    }\n\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * val obj = new MedianFinder()\n * obj.addNum(num)\n * val param_2 = obj.findMedian()\n */"}, {"value": "rust", "text": "Rust", "defaultCode": "struct MedianFinder {\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 MedianFinder {\n\n    fn new() -> Self {\n        \n    }\n    \n    fn add_num(&self, num: i32) {\n        \n    }\n    \n    fn find_median(&self) -> f64 {\n        \n    }\n}\n\n/**\n * Your MedianFinder object will be instantiated and called as such:\n * let obj = MedianFinder::new();\n * obj.add_num(num);\n * let ret_2: f64 = obj.find_median();\n */"}, {"value": "racket", "text": "Racket", "defaultCode": "(define median-finder%\n  (class object%\n    (super-new)\n    \n    (init-field)\n    \n    ; add-num : exact-integer? -> void?\n    (define/public (add-num num)\n      )\n    ; find-median : -> flonum?\n    (define/public (find-median)\n      )))\n\n;; Your median-finder% object will be instantiated and called as such:\n;; (define obj (new median-finder%))\n;; (send obj add-num num)\n;; (define param_2 (send obj find-median))"}, {"value": "erlang", "text": "Erlang", "defaultCode": "-spec median_finder_init_() -> any().\nmedian_finder_init_() ->\n  .\n\n-spec median_finder_add_num(Num :: integer()) -> any().\nmedian_finder_add_num(Num) ->\n  .\n\n-spec median_finder_find_median() -> float().\nmedian_finder_find_median() ->\n  .\n\n\n%% Your functions will be called as such:\n%% median_finder_init_(),\n%% median_finder_add_num(Num),\n%% Param_2 = median_finder_find_median(),\n\n%% median_finder_init_ will be called before every test case, in which you can do some necessary initializations."}, {"value": "elixir", "text": "Elixir", "defaultCode": "defmodule MedianFinder do\n  @spec init_() :: any\n  def init_() do\n    \n  end\n\n  @spec add_num(num :: integer) :: any\n  def add_num(num) do\n    \n  end\n\n  @spec find_median() :: float\n  def find_median() do\n    \n  end\nend\n\n# Your functions will be called as such:\n# MedianFinder.init_()\n# MedianFinder.add_num(num)\n# param_2 = MedianFinder.find_median()\n\n# MedianFinder.init_ will be called before every test case, in which you can do some necessary initializations."}]
{
  "classname": "MedianFinder",
  "constructor": {
    "params": []
  },
  "methods": [
    {
      "params": [
        {
          "type": "integer",
          "name": "num"
        }
      ],
      "name": "addNum",
      "return": {
        "type": "void"
      }
    },
    {
      "params": [],
      "name": "findMedian",
      "return": {
        "type": "double"
      }
    }
  ],
  "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>"]}
['Two Pointers', 'Design', 'Sorting', 'Heap (Priority Queue)', 'Data Stream']