Design Underground System
<p>An underground railway system is keeping track of customer travel times between different stations. They are using this data to calculate the average time it takes to travel from one station to another.</p>

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

<ul>
	<li><code>void checkIn(int id, string stationName, int t)</code>

	<ul>
		<li>A customer with a card ID equal to <code>id</code>, checks in at the station <code>stationName</code> at time <code>t</code>.</li>
		<li>A customer can only be checked into one place at a time.</li>
	</ul>
	</li>
	<li><code>void checkOut(int id, string stationName, int t)</code>
	<ul>
		<li>A customer with a card ID equal to <code>id</code>, checks out from the station <code>stationName</code> at time <code>t</code>.</li>
	</ul>
	</li>
	<li><code>double getAverageTime(string startStation, string endStation)</code>
	<ul>
		<li>Returns the average time it takes to travel from <code>startStation</code> to <code>endStation</code>.</li>
		<li>The average time is computed from all the previous traveling times from <code>startStation</code> to <code>endStation</code> that happened <strong>directly</strong>, meaning a check in at <code>startStation</code> followed by a check out from <code>endStation</code>.</li>
		<li>The time it takes to travel from <code>startStation</code> to <code>endStation</code> <strong>may be different</strong> from the time it takes to travel from <code>endStation</code> to <code>startStation</code>.</li>
		<li>There will be at least one customer that has traveled from <code>startStation</code> to <code>endStation</code> before <code>getAverageTime</code> is called.</li>
	</ul>
	</li>
</ul>

<p>You may assume all calls to the <code>checkIn</code> and <code>checkOut</code> methods are consistent. If a customer checks in at time <code>t<sub>1</sub></code> then checks out at time <code>t<sub>2</sub></code>, then <code>t<sub>1</sub> &lt; t<sub>2</sub></code>. All events happen in chronological order.</p>

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

<pre>
<strong>Input</strong>
[&quot;UndergroundSystem&quot;,&quot;checkIn&quot;,&quot;checkIn&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;checkOut&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;getAverageTime&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;]
[[],[45,&quot;Leyton&quot;,3],[32,&quot;Paradise&quot;,8],[27,&quot;Leyton&quot;,10],[45,&quot;Waterloo&quot;,15],[27,&quot;Waterloo&quot;,20],[32,&quot;Cambridge&quot;,22],[&quot;Paradise&quot;,&quot;Cambridge&quot;],[&quot;Leyton&quot;,&quot;Waterloo&quot;],[10,&quot;Leyton&quot;,24],[&quot;Leyton&quot;,&quot;Waterloo&quot;],[10,&quot;Waterloo&quot;,38],[&quot;Leyton&quot;,&quot;Waterloo&quot;]]

<strong>Output</strong>
[null,null,null,null,null,null,null,14.00000,11.00000,null,11.00000,null,12.00000]

<strong>Explanation</strong>
UndergroundSystem undergroundSystem = new UndergroundSystem();
undergroundSystem.checkIn(45, &quot;Leyton&quot;, 3);
undergroundSystem.checkIn(32, &quot;Paradise&quot;, 8);
undergroundSystem.checkIn(27, &quot;Leyton&quot;, 10);
undergroundSystem.checkOut(45, &quot;Waterloo&quot;, 15);  // Customer 45 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 15-3 = 12
undergroundSystem.checkOut(27, &quot;Waterloo&quot;, 20);  // Customer 27 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 20-10 = 10
undergroundSystem.checkOut(32, &quot;Cambridge&quot;, 22); // Customer 32 &quot;Paradise&quot; -&gt; &quot;Cambridge&quot; in 22-8 = 14
undergroundSystem.getAverageTime(&quot;Paradise&quot;, &quot;Cambridge&quot;); // return 14.00000. One trip &quot;Paradise&quot; -&gt; &quot;Cambridge&quot;, (14) / 1 = 14
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 11.00000. Two trips &quot;Leyton&quot; -&gt; &quot;Waterloo&quot;, (10 + 12) / 2 = 11
undergroundSystem.checkIn(10, &quot;Leyton&quot;, 24);
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 11.00000
undergroundSystem.checkOut(10, &quot;Waterloo&quot;, 38);  // Customer 10 &quot;Leyton&quot; -&gt; &quot;Waterloo&quot; in 38-24 = 14
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Waterloo&quot;);    // return 12.00000. Three trips &quot;Leyton&quot; -&gt; &quot;Waterloo&quot;, (10 + 12 + 14) / 3 = 12
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input</strong>
[&quot;UndergroundSystem&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;,&quot;checkIn&quot;,&quot;checkOut&quot;,&quot;getAverageTime&quot;]
[[],[10,&quot;Leyton&quot;,3],[10,&quot;Paradise&quot;,8],[&quot;Leyton&quot;,&quot;Paradise&quot;],[5,&quot;Leyton&quot;,10],[5,&quot;Paradise&quot;,16],[&quot;Leyton&quot;,&quot;Paradise&quot;],[2,&quot;Leyton&quot;,21],[2,&quot;Paradise&quot;,30],[&quot;Leyton&quot;,&quot;Paradise&quot;]]

<strong>Output</strong>
[null,null,null,5.00000,null,null,5.50000,null,null,6.66667]

<strong>Explanation</strong>
UndergroundSystem undergroundSystem = new UndergroundSystem();
undergroundSystem.checkIn(10, &quot;Leyton&quot;, 3);
undergroundSystem.checkOut(10, &quot;Paradise&quot;, 8); // Customer 10 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 8-3 = 5
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 5.00000, (5) / 1 = 5
undergroundSystem.checkIn(5, &quot;Leyton&quot;, 10);
undergroundSystem.checkOut(5, &quot;Paradise&quot;, 16); // Customer 5 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 16-10 = 6
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 5.50000, (5 + 6) / 2 = 5.5
undergroundSystem.checkIn(2, &quot;Leyton&quot;, 21);
undergroundSystem.checkOut(2, &quot;Paradise&quot;, 30); // Customer 2 &quot;Leyton&quot; -&gt; &quot;Paradise&quot; in 30-21 = 9
undergroundSystem.getAverageTime(&quot;Leyton&quot;, &quot;Paradise&quot;); // return 6.66667, (5 + 6 + 9) / 3 = 6.66667
</pre>

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

<ul>
	<li><code>1 &lt;= id, t &lt;= 10<sup>6</sup></code></li>
	<li><code>1 &lt;= stationName.length, startStation.length, endStation.length &lt;= 10</code></li>
	<li>All strings consist of uppercase and lowercase English letters and digits.</li>
	<li>There will be at most <code>2 * 10<sup>4</sup></code> calls <strong>in total</strong> to <code>checkIn</code>, <code>checkOut</code>, and <code>getAverageTime</code>.</li>
	<li>Answers within <code>10<sup>-5</sup></code> of the actual value will be accepted.</li>
</ul>

['design-bitset']
[]
[{"value": "cpp", "text": "C++", "defaultCode": "class UndergroundSystem {\npublic:\n    UndergroundSystem() {\n        \n    }\n    \n    void checkIn(int id, string stationName, int t) {\n        \n    }\n    \n    void checkOut(int id, string stationName, int t) {\n        \n    }\n    \n    double getAverageTime(string startStation, string endStation) {\n        \n    }\n};\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * UndergroundSystem* obj = new UndergroundSystem();\n * obj->checkIn(id,stationName,t);\n * obj->checkOut(id,stationName,t);\n * double param_3 = obj->getAverageTime(startStation,endStation);\n */"}, {"value": "java", "text": "Java", "defaultCode": "class UndergroundSystem {\n\n    public UndergroundSystem() {\n        \n    }\n    \n    public void checkIn(int id, String stationName, int t) {\n        \n    }\n    \n    public void checkOut(int id, String stationName, int t) {\n        \n    }\n    \n    public double getAverageTime(String startStation, String endStation) {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * UndergroundSystem obj = new UndergroundSystem();\n * obj.checkIn(id,stationName,t);\n * obj.checkOut(id,stationName,t);\n * double param_3 = obj.getAverageTime(startStation,endStation);\n */"}, {"value": "python", "text": "Python", "defaultCode": "class UndergroundSystem(object):\n\n    def __init__(self):\n        \n\n    def checkIn(self, id, stationName, t):\n        \"\"\"\n        :type id: int\n        :type stationName: str\n        :type t: int\n        :rtype: None\n        \"\"\"\n        \n\n    def checkOut(self, id, stationName, t):\n        \"\"\"\n        :type id: int\n        :type stationName: str\n        :type t: int\n        :rtype: None\n        \"\"\"\n        \n\n    def getAverageTime(self, startStation, endStation):\n        \"\"\"\n        :type startStation: str\n        :type endStation: str\n        :rtype: float\n        \"\"\"\n        \n\n\n# Your UndergroundSystem object will be instantiated and called as such:\n# obj = UndergroundSystem()\n# obj.checkIn(id,stationName,t)\n# obj.checkOut(id,stationName,t)\n# param_3 = obj.getAverageTime(startStation,endStation)"}, {"value": "python3", "text": "Python3", "defaultCode": "class UndergroundSystem:\n\n    def __init__(self):\n        \n\n    def checkIn(self, id: int, stationName: str, t: int) -> None:\n        \n\n    def checkOut(self, id: int, stationName: str, t: int) -> None:\n        \n\n    def getAverageTime(self, startStation: str, endStation: str) -> float:\n        \n\n\n# Your UndergroundSystem object will be instantiated and called as such:\n# obj = UndergroundSystem()\n# obj.checkIn(id,stationName,t)\n# obj.checkOut(id,stationName,t)\n# param_3 = obj.getAverageTime(startStation,endStation)"}, {"value": "c", "text": "C", "defaultCode": "\n\n\ntypedef struct {\n    \n} UndergroundSystem;\n\n\nUndergroundSystem* undergroundSystemCreate() {\n    \n}\n\nvoid undergroundSystemCheckIn(UndergroundSystem* obj, int id, char* stationName, int t) {\n    \n}\n\nvoid undergroundSystemCheckOut(UndergroundSystem* obj, int id, char* stationName, int t) {\n    \n}\n\ndouble undergroundSystemGetAverageTime(UndergroundSystem* obj, char* startStation, char* endStation) {\n    \n}\n\nvoid undergroundSystemFree(UndergroundSystem* obj) {\n    \n}\n\n/**\n * Your UndergroundSystem struct will be instantiated and called as such:\n * UndergroundSystem* obj = undergroundSystemCreate();\n * undergroundSystemCheckIn(obj, id, stationName, t);\n \n * undergroundSystemCheckOut(obj, id, stationName, t);\n \n * double param_3 = undergroundSystemGetAverageTime(obj, startStation, endStation);\n \n * undergroundSystemFree(obj);\n*/"}, {"value": "csharp", "text": "C#", "defaultCode": "public class UndergroundSystem {\n\n    public UndergroundSystem() {\n        \n    }\n    \n    public void CheckIn(int id, string stationName, int t) {\n        \n    }\n    \n    public void CheckOut(int id, string stationName, int t) {\n        \n    }\n    \n    public double GetAverageTime(string startStation, string endStation) {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * UndergroundSystem obj = new UndergroundSystem();\n * obj.CheckIn(id,stationName,t);\n * obj.CheckOut(id,stationName,t);\n * double param_3 = obj.GetAverageTime(startStation,endStation);\n */"}, {"value": "javascript", "text": "JavaScript", "defaultCode": "\nvar UndergroundSystem = function() {\n    \n};\n\n/** \n * @param {number} id \n * @param {string} stationName \n * @param {number} t\n * @return {void}\n */\nUndergroundSystem.prototype.checkIn = function(id, stationName, t) {\n    \n};\n\n/** \n * @param {number} id \n * @param {string} stationName \n * @param {number} t\n * @return {void}\n */\nUndergroundSystem.prototype.checkOut = function(id, stationName, t) {\n    \n};\n\n/** \n * @param {string} startStation \n * @param {string} endStation\n * @return {number}\n */\nUndergroundSystem.prototype.getAverageTime = function(startStation, endStation) {\n    \n};\n\n/** \n * Your UndergroundSystem object will be instantiated and called as such:\n * var obj = new UndergroundSystem()\n * obj.checkIn(id,stationName,t)\n * obj.checkOut(id,stationName,t)\n * var param_3 = obj.getAverageTime(startStation,endStation)\n */"}, {"value": "typescript", "text": "TypeScript", "defaultCode": "class UndergroundSystem {\n    constructor() {\n        \n    }\n\n    checkIn(id: number, stationName: string, t: number): void {\n        \n    }\n\n    checkOut(id: number, stationName: string, t: number): void {\n        \n    }\n\n    getAverageTime(startStation: string, endStation: string): number {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * var obj = new UndergroundSystem()\n * obj.checkIn(id,stationName,t)\n * obj.checkOut(id,stationName,t)\n * var param_3 = obj.getAverageTime(startStation,endStation)\n */"}, {"value": "php", "text": "PHP", "defaultCode": "class UndergroundSystem {\n    /**\n     */\n    function __construct() {\n        \n    }\n  \n    /**\n     * @param Integer $id\n     * @param String $stationName\n     * @param Integer $t\n     * @return NULL\n     */\n    function checkIn($id, $stationName, $t) {\n        \n    }\n  \n    /**\n     * @param Integer $id\n     * @param String $stationName\n     * @param Integer $t\n     * @return NULL\n     */\n    function checkOut($id, $stationName, $t) {\n        \n    }\n  \n    /**\n     * @param String $startStation\n     * @param String $endStation\n     * @return Float\n     */\n    function getAverageTime($startStation, $endStation) {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * $obj = UndergroundSystem();\n * $obj->checkIn($id, $stationName, $t);\n * $obj->checkOut($id, $stationName, $t);\n * $ret_3 = $obj->getAverageTime($startStation, $endStation);\n */"}, {"value": "swift", "text": "Swift", "defaultCode": "\nclass UndergroundSystem {\n\n    init() {\n        \n    }\n    \n    func checkIn(_ id: Int, _ stationName: String, _ t: Int) {\n        \n    }\n    \n    func checkOut(_ id: Int, _ stationName: String, _ t: Int) {\n        \n    }\n    \n    func getAverageTime(_ startStation: String, _ endStation: String) -> Double {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * let obj = UndergroundSystem()\n * obj.checkIn(id, stationName, t)\n * obj.checkOut(id, stationName, t)\n * let ret_3: Double = obj.getAverageTime(startStation, endStation)\n */"}, {"value": "kotlin", "text": "Kotlin", "defaultCode": "class UndergroundSystem() {\n\n    fun checkIn(id: Int, stationName: String, t: Int) {\n        \n    }\n\n    fun checkOut(id: Int, stationName: String, t: Int) {\n        \n    }\n\n    fun getAverageTime(startStation: String, endStation: String): Double {\n        \n    }\n\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * var obj = UndergroundSystem()\n * obj.checkIn(id,stationName,t)\n * obj.checkOut(id,stationName,t)\n * var param_3 = obj.getAverageTime(startStation,endStation)\n */"}, {"value": "dart", "text": "Dart", "defaultCode": "class UndergroundSystem {\n\n  UndergroundSystem() {\n    \n  }\n  \n  void checkIn(int id, String stationName, int t) {\n    \n  }\n  \n  void checkOut(int id, String stationName, int t) {\n    \n  }\n  \n  double getAverageTime(String startStation, String endStation) {\n    \n  }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * UndergroundSystem obj = UndergroundSystem();\n * obj.checkIn(id,stationName,t);\n * obj.checkOut(id,stationName,t);\n * double param3 = obj.getAverageTime(startStation,endStation);\n */"}, {"value": "golang", "text": "Go", "defaultCode": "type UndergroundSystem struct {\n    \n}\n\n\nfunc Constructor() UndergroundSystem {\n    \n}\n\n\nfunc (this *UndergroundSystem) CheckIn(id int, stationName string, t int)  {\n    \n}\n\n\nfunc (this *UndergroundSystem) CheckOut(id int, stationName string, t int)  {\n    \n}\n\n\nfunc (this *UndergroundSystem) GetAverageTime(startStation string, endStation string) float64 {\n    \n}\n\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * obj := Constructor();\n * obj.CheckIn(id,stationName,t);\n * obj.CheckOut(id,stationName,t);\n * param_3 := obj.GetAverageTime(startStation,endStation);\n */"}, {"value": "ruby", "text": "Ruby", "defaultCode": "class UndergroundSystem\n    def initialize()\n        \n    end\n\n\n=begin\n    :type id: Integer\n    :type station_name: String\n    :type t: Integer\n    :rtype: Void\n=end\n    def check_in(id, station_name, t)\n        \n    end\n\n\n=begin\n    :type id: Integer\n    :type station_name: String\n    :type t: Integer\n    :rtype: Void\n=end\n    def check_out(id, station_name, t)\n        \n    end\n\n\n=begin\n    :type start_station: String\n    :type end_station: String\n    :rtype: Float\n=end\n    def get_average_time(start_station, end_station)\n        \n    end\n\n\nend\n\n# Your UndergroundSystem object will be instantiated and called as such:\n# obj = UndergroundSystem.new()\n# obj.check_in(id, station_name, t)\n# obj.check_out(id, station_name, t)\n# param_3 = obj.get_average_time(start_station, end_station)"}, {"value": "scala", "text": "Scala", "defaultCode": "class UndergroundSystem() {\n\n    def checkIn(id: Int, stationName: String, t: Int): Unit = {\n        \n    }\n\n    def checkOut(id: Int, stationName: String, t: Int): Unit = {\n        \n    }\n\n    def getAverageTime(startStation: String, endStation: String): Double = {\n        \n    }\n\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * val obj = new UndergroundSystem()\n * obj.checkIn(id,stationName,t)\n * obj.checkOut(id,stationName,t)\n * val param_3 = obj.getAverageTime(startStation,endStation)\n */"}, {"value": "rust", "text": "Rust", "defaultCode": "struct UndergroundSystem {\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 UndergroundSystem {\n\n    fn new() -> Self {\n        \n    }\n    \n    fn check_in(&self, id: i32, station_name: String, t: i32) {\n        \n    }\n    \n    fn check_out(&self, id: i32, station_name: String, t: i32) {\n        \n    }\n    \n    fn get_average_time(&self, start_station: String, end_station: String) -> f64 {\n        \n    }\n}\n\n/**\n * Your UndergroundSystem object will be instantiated and called as such:\n * let obj = UndergroundSystem::new();\n * obj.check_in(id, stationName, t);\n * obj.check_out(id, stationName, t);\n * let ret_3: f64 = obj.get_average_time(startStation, endStation);\n */"}, {"value": "racket", "text": "Racket", "defaultCode": "(define underground-system%\n  (class object%\n    (super-new)\n    \n    (init-field)\n    \n    ; check-in : exact-integer? string? exact-integer? -> void?\n    (define/public (check-in id station-name t)\n      )\n    ; check-out : exact-integer? string? exact-integer? -> void?\n    (define/public (check-out id station-name t)\n      )\n    ; get-average-time : string? string? -> flonum?\n    (define/public (get-average-time start-station end-station)\n      )))\n\n;; Your underground-system% object will be instantiated and called as such:\n;; (define obj (new underground-system%))\n;; (send obj check-in id station-name t)\n;; (send obj check-out id station-name t)\n;; (define param_3 (send obj get-average-time start-station end-station))"}, {"value": "erlang", "text": "Erlang", "defaultCode": "-spec underground_system_init_() -> any().\nunderground_system_init_() ->\n  .\n\n-spec underground_system_check_in(Id :: integer(), StationName :: unicode:unicode_binary(), T :: integer()) -> any().\nunderground_system_check_in(Id, StationName, T) ->\n  .\n\n-spec underground_system_check_out(Id :: integer(), StationName :: unicode:unicode_binary(), T :: integer()) -> any().\nunderground_system_check_out(Id, StationName, T) ->\n  .\n\n-spec underground_system_get_average_time(StartStation :: unicode:unicode_binary(), EndStation :: unicode:unicode_binary()) -> float().\nunderground_system_get_average_time(StartStation, EndStation) ->\n  .\n\n\n%% Your functions will be called as such:\n%% underground_system_init_(),\n%% underground_system_check_in(Id, StationName, T),\n%% underground_system_check_out(Id, StationName, T),\n%% Param_3 = underground_system_get_average_time(StartStation, EndStation),\n\n%% underground_system_init_ will be called before every test case, in which you can do some necessary initializations."}, {"value": "elixir", "text": "Elixir", "defaultCode": "defmodule UndergroundSystem do\n  @spec init_() :: any\n  def init_() do\n    \n  end\n\n  @spec check_in(id :: integer, station_name :: String.t, t :: integer) :: any\n  def check_in(id, station_name, t) do\n    \n  end\n\n  @spec check_out(id :: integer, station_name :: String.t, t :: integer) :: any\n  def check_out(id, station_name, t) do\n    \n  end\n\n  @spec get_average_time(start_station :: String.t, end_station :: String.t) :: float\n  def get_average_time(start_station, end_station) do\n    \n  end\nend\n\n# Your functions will be called as such:\n# UndergroundSystem.init_()\n# UndergroundSystem.check_in(id, station_name, t)\n# UndergroundSystem.check_out(id, station_name, t)\n# param_3 = UndergroundSystem.get_average_time(start_station, end_station)\n\n# UndergroundSystem.init_ will be called before every test case, in which you can do some necessary initializations."}]
{
  "classname": "UndergroundSystem",
  "constructor": {
    "params": []
  },
  "methods": [
    {
      "params": [
        {
          "type": "integer",
          "name": "id"
        },
        {
          "type": "string",
          "name": "stationName"
        },
        {
          "type": "integer",
          "name": "t"
        }
      ],
      "name": "checkIn",
      "return": {
        "type": "void"
      }
    },
    {
      "params": [
        {
          "type": "integer",
          "name": "id"
        },
        {
          "type": "string",
          "name": "stationName"
        },
        {
          "type": "integer",
          "name": "t"
        }
      ],
      "name": "checkOut",
      "return": {
        "type": "void"
      }
    },
    {
      "params": [
        {
          "type": "string",
          "name": "startStation"
        },
        {
          "type": "string",
          "name": "endStation"
        }
      ],
      "name": "getAverageTime",
      "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>"]}
['Hash Table', 'String', 'Design']