Longest Uploaded Prefix
<p>You are given a stream of <code>n</code> videos, each represented by a <strong>distinct</strong> number from <code>1</code> to <code>n</code> that you need to &quot;upload&quot; to a server. You need to implement a data structure that calculates the length of the <strong>longest uploaded prefix</strong> at various points in the upload process.</p>

<p>We consider <code>i</code> to be an uploaded prefix if all videos in the range <code>1</code> to <code>i</code> (<strong>inclusive</strong>) have been uploaded to the server. The longest uploaded prefix is the <strong>maximum </strong>value of <code>i</code> that satisfies this definition.<br />
<br />
Implement the <code>LUPrefix </code>class:</p>

<ul>
	<li><code>LUPrefix(int n)</code> Initializes the object for a stream of <code>n</code> videos.</li>
	<li><code>void upload(int video)</code> Uploads <code>video</code> to the server.</li>
	<li><code>int longest()</code> Returns the length of the <strong>longest uploaded prefix</strong> defined above.</li>
</ul>

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

<pre>
<strong>Input</strong>
[&quot;LUPrefix&quot;, &quot;upload&quot;, &quot;longest&quot;, &quot;upload&quot;, &quot;longest&quot;, &quot;upload&quot;, &quot;longest&quot;]
[[4], [3], [], [1], [], [2], []]
<strong>Output</strong>
[null, null, 0, null, 1, null, 3]

<strong>Explanation</strong>
LUPrefix server = new LUPrefix(4);   // Initialize a stream of 4 videos.
server.upload(3);                    // Upload video 3.
server.longest();                    // Since video 1 has not been uploaded yet, there is no prefix.
                                     // So, we return 0.
server.upload(1);                    // Upload video 1.
server.longest();                    // The prefix [1] is the longest uploaded prefix, so we return 1.
server.upload(2);                    // Upload video 2.
server.longest();                    // The prefix [1,2,3] is the longest uploaded prefix, so we return 3.
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= video &lt;= n</code></li>
	<li>All values of <code>video</code> are <strong>distinct</strong>.</li>
	<li>At most <code>2 * 10<sup>5</sup></code> calls <strong>in total</strong> will be made to <code>upload</code> and <code>longest</code>.</li>
	<li>At least one call will be made to <code>longest</code>.</li>
</ul>

['design-an-ordered-stream']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "class LUPrefix {\npublic:\n    LUPrefix(int n) {\n        \n    }\n    \n    void upload(int video) {\n        \n    }\n    \n    int longest() {\n        \n    }\n};\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * LUPrefix* obj = new LUPrefix(n);\n * obj->upload(video);\n * int param_2 = obj->longest();\n */"}, {"value": "java", "text": "Java", "defaultCode": "class LUPrefix {\n\n    public LUPrefix(int n) {\n        \n    }\n    \n    public void upload(int video) {\n        \n    }\n    \n    public int longest() {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * LUPrefix obj = new LUPrefix(n);\n * obj.upload(video);\n * int param_2 = obj.longest();\n */"}, {"value": "python", "text": "Python", "defaultCode": "class LUPrefix(object):\n\n    def __init__(self, n):\n        \"\"\"\n        :type n: int\n        \"\"\"\n        \n\n    def upload(self, video):\n        \"\"\"\n        :type video: int\n        :rtype: None\n        \"\"\"\n        \n\n    def longest(self):\n        \"\"\"\n        :rtype: int\n        \"\"\"\n        \n\n\n# Your LUPrefix object will be instantiated and called as such:\n# obj = LUPrefix(n)\n# obj.upload(video)\n# param_2 = obj.longest()"}, {"value": "python3", "text": "Python3", "defaultCode": "class LUPrefix:\n\n    def __init__(self, n: int):\n        \n\n    def upload(self, video: int) -> None:\n        \n\n    def longest(self) -> int:\n        \n\n\n# Your LUPrefix object will be instantiated and called as such:\n# obj = LUPrefix(n)\n# obj.upload(video)\n# param_2 = obj.longest()"}, {"value": "c", "text": "C", "defaultCode": "\n\n\ntypedef struct {\n    \n} LUPrefix;\n\n\nLUPrefix* lUPrefixCreate(int n) {\n    \n}\n\nvoid lUPrefixUpload(LUPrefix* obj, int video) {\n    \n}\n\nint lUPrefixLongest(LUPrefix* obj) {\n    \n}\n\nvoid lUPrefixFree(LUPrefix* obj) {\n    \n}\n\n/**\n * Your LUPrefix struct will be instantiated and called as such:\n * LUPrefix* obj = lUPrefixCreate(n);\n * lUPrefixUpload(obj, video);\n \n * int param_2 = lUPrefixLongest(obj);\n \n * lUPrefixFree(obj);\n*/"}, {"value": "csharp", "text": "C#", "defaultCode": "public class LUPrefix {\n\n    public LUPrefix(int n) {\n        \n    }\n    \n    public void Upload(int video) {\n        \n    }\n    \n    public int Longest() {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * LUPrefix obj = new LUPrefix(n);\n * obj.Upload(video);\n * int param_2 = obj.Longest();\n */"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "/**\n * @param {number} n\n */\nvar LUPrefix = function(n) {\n    \n};\n\n/** \n * @param {number} video\n * @return {void}\n */\nLUPrefix.prototype.upload = function(video) {\n    \n};\n\n/**\n * @return {number}\n */\nLUPrefix.prototype.longest = function() {\n    \n};\n\n/** \n * Your LUPrefix object will be instantiated and called as such:\n * var obj = new LUPrefix(n)\n * obj.upload(video)\n * var param_2 = obj.longest()\n */"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "class LUPrefix {\n    constructor(n: number) {\n        \n    }\n\n    upload(video: number): void {\n        \n    }\n\n    longest(): number {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * var obj = new LUPrefix(n)\n * obj.upload(video)\n * var param_2 = obj.longest()\n */"}, {"value": "php", "text": "PHP", "defaultCode": "class LUPrefix {\n    /**\n     * @param Integer $n\n     */\n    function __construct($n) {\n        \n    }\n  \n    /**\n     * @param Integer $video\n     * @return NULL\n     */\n    function upload($video) {\n        \n    }\n  \n    /**\n     * @return Integer\n     */\n    function longest() {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * $obj = LUPrefix($n);\n * $obj->upload($video);\n * $ret_2 = $obj->longest();\n */"}, {"value": "swift", "text": "Swift", "defaultCode": "\nclass LUPrefix {\n\n    init(_ n: Int) {\n        \n    }\n    \n    func upload(_ video: Int) {\n        \n    }\n    \n    func longest() -> Int {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * let obj = LUPrefix(n)\n * obj.upload(video)\n * let ret_2: Int = obj.longest()\n */"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "class LUPrefix(n: Int) {\n\n    fun upload(video: Int) {\n        \n    }\n\n    fun longest(): Int {\n        \n    }\n\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * var obj = LUPrefix(n)\n * obj.upload(video)\n * var param_2 = obj.longest()\n */"}, {"value": "dart", "text": "Dart", "defaultCode": "class LUPrefix {\n\n  LUPrefix(int n) {\n    \n  }\n  \n  void upload(int video) {\n    \n  }\n  \n  int longest() {\n    \n  }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * LUPrefix obj = LUPrefix(n);\n * obj.upload(video);\n * int param2 = obj.longest();\n */"}, {"value": "golang", "text": "Go", "defaultCode": "type LUPrefix struct {\n    \n}\n\n\nfunc Constructor(n int) LUPrefix {\n    \n}\n\n\nfunc (this *LUPrefix) Upload(video int)  {\n    \n}\n\n\nfunc (this *LUPrefix) Longest() int {\n    \n}\n\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * obj := Constructor(n);\n * obj.Upload(video);\n * param_2 := obj.Longest();\n */"}, {"value": "ruby", "text": "Ruby", "defaultCode": "class LUPrefix\n\n=begin\n    :type n: Integer\n=end\n    def initialize(n)\n        \n    end\n\n\n=begin\n    :type video: Integer\n    :rtype: Void\n=end\n    def upload(video)\n        \n    end\n\n\n=begin\n    :rtype: Integer\n=end\n    def longest()\n        \n    end\n\n\nend\n\n# Your LUPrefix object will be instantiated and called as such:\n# obj = LUPrefix.new(n)\n# obj.upload(video)\n# param_2 = obj.longest()"}, {"value": "scala", "text": "Scala", "defaultCode": "class LUPrefix(_n: Int) {\n\n    def upload(video: Int): Unit = {\n        \n    }\n\n    def longest(): Int = {\n        \n    }\n\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * val obj = new LUPrefix(n)\n * obj.upload(video)\n * val param_2 = obj.longest()\n */"}, {"value": "rust", "text": "Rust", "defaultCode": "struct LUPrefix {\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 LUPrefix {\n\n    fn new(n: i32) -> Self {\n        \n    }\n    \n    fn upload(&self, video: i32) {\n        \n    }\n    \n    fn longest(&self) -> i32 {\n        \n    }\n}\n\n/**\n * Your LUPrefix object will be instantiated and called as such:\n * let obj = LUPrefix::new(n);\n * obj.upload(video);\n * let ret_2: i32 = obj.longest();\n */"}, {"value": "racket", "text": "Racket", "defaultCode": "(define lu-prefix%\n  (class object%\n    (super-new)\n    \n    ; n : exact-integer?\n    (init-field\n      n)\n    \n    ; upload : exact-integer? -> void?\n    (define/public (upload video)\n      )\n    ; longest : -> exact-integer?\n    (define/public (longest)\n      )))\n\n;; Your lu-prefix% object will be instantiated and called as such:\n;; (define obj (new lu-prefix% [n n]))\n;; (send obj upload video)\n;; (define param_2 (send obj longest))"}, {"value": "erlang", "text": "Erlang", "defaultCode": "-spec lu_prefix_init_(N :: integer()) -> any().\nlu_prefix_init_(N) ->\n  .\n\n-spec lu_prefix_upload(Video :: integer()) -> any().\nlu_prefix_upload(Video) ->\n  .\n\n-spec lu_prefix_longest() -> integer().\nlu_prefix_longest() ->\n  .\n\n\n%% Your functions will be called as such:\n%% lu_prefix_init_(N),\n%% lu_prefix_upload(Video),\n%% Param_2 = lu_prefix_longest(),\n\n%% lu_prefix_init_ will be called before every test case, in which you can do some necessary initializations."}, {"value": "elixir", "text": "Elixir", "defaultCode": "defmodule LUPrefix do\n  @spec init_(n :: integer) :: any\n  def init_(n) do\n    \n  end\n\n  @spec upload(video :: integer) :: any\n  def upload(video) do\n    \n  end\n\n  @spec longest() :: integer\n  def longest() do\n    \n  end\nend\n\n# Your functions will be called as such:\n# LUPrefix.init_(n)\n# LUPrefix.upload(video)\n# param_2 = LUPrefix.longest()\n\n# LUPrefix.init_ will be called before every test case, in which you can do some necessary initializations."}]
{
  "classname": "LUPrefix",
  "constructor": {
    "params": [
      {
        "type": "integer",
        "name": "n"
      }
    ]
  },
  "methods": [
    {
      "params": [
        {
          "type": "integer",
          "name": "video"
        }
      ],
      "name": "upload",
      "return": {
        "type": "void"
      }
    },
    {
      "params": [],
      "return": {
        "type": "integer"
      },
      "name": "longest"
    }
  ],
  "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>"]}
['Binary Search', 'Union Find', 'Design', 'Binary Indexed Tree', 'Segment Tree', 'Heap (Priority Queue)', 'Ordered Set']