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"questionId": "2413",
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"title": "Smallest Number in Infinite Set",
"titleSlug": "smallest-number-in-infinite-set",
"content": "<p>You have a set which contains all positive integers <code>[1, 2, 3, 4, 5, ...]</code>.</p>\n\n<p>Implement the <code>SmallestInfiniteSet</code> class:</p>\n\n<ul>\n\t<li><code>SmallestInfiniteSet()</code> Initializes the <strong>SmallestInfiniteSet</strong> object to contain <strong>all</strong> positive integers.</li>\n\t<li><code>int popSmallest()</code> <strong>Removes</strong> and returns the smallest integer contained in the infinite set.</li>\n\t<li><code>void addBack(int num)</code> <strong>Adds</strong> a positive integer <code>num</code> back into the infinite set, if it is <strong>not</strong> already in the infinite set.</li>\n</ul>\n\n<p> </p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input</strong>\n["SmallestInfiniteSet", "addBack", "popSmallest", "popSmallest", "popSmallest", "addBack", "popSmallest", "popSmallest", "popSmallest"]\n[[], [2], [], [], [], [1], [], [], []]\n<strong>Output</strong>\n[null, null, 1, 2, 3, null, 1, 4, 5]\n\n<strong>Explanation</strong>\nSmallestInfiniteSet smallestInfiniteSet = new SmallestInfiniteSet();\nsmallestInfiniteSet.addBack(2); // 2 is already in the set, so no change is made.\nsmallestInfiniteSet.popSmallest(); // return 1, since 1 is the smallest number, and remove it from the set.\nsmallestInfiniteSet.popSmallest(); // return 2, and remove it from the set.\nsmallestInfiniteSet.popSmallest(); // return 3, and remove it from the set.\nsmallestInfiniteSet.addBack(1); // 1 is added back to the set.\nsmallestInfiniteSet.popSmallest(); // return 1, since 1 was added back to the set and\n // is the smallest number, and remove it from the set.\nsmallestInfiniteSet.popSmallest(); // return 4, and remove it from the set.\nsmallestInfiniteSet.popSmallest(); // return 5, and remove it from the set.\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 <= num <= 1000</code></li>\n\t<li>At most <code>1000</code> calls will be made <strong>in total</strong> to <code>popSmallest</code> and <code>addBack</code>.</li>\n</ul>\n",
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"lang": "C++",
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"code": "class SmallestInfiniteSet {\npublic:\n SmallestInfiniteSet() {\n \n }\n \n int popSmallest() {\n \n }\n \n void addBack(int num) {\n \n }\n};\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * SmallestInfiniteSet* obj = new SmallestInfiniteSet();\n * int param_1 = obj->popSmallest();\n * obj->addBack(num);\n */",
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"lang": "Java",
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"code": "class SmallestInfiniteSet {\n\n public SmallestInfiniteSet() {\n \n }\n \n public int popSmallest() {\n \n }\n \n public void addBack(int num) {\n \n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * SmallestInfiniteSet obj = new SmallestInfiniteSet();\n * int param_1 = obj.popSmallest();\n * obj.addBack(num);\n */",
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"lang": "Python",
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"code": "class SmallestInfiniteSet(object):\n\n def __init__(self):\n \n\n def popSmallest(self):\n \"\"\"\n :rtype: int\n \"\"\"\n \n\n def addBack(self, num):\n \"\"\"\n :type num: int\n :rtype: None\n \"\"\"\n \n\n\n# Your SmallestInfiniteSet object will be instantiated and called as such:\n# obj = SmallestInfiniteSet()\n# param_1 = obj.popSmallest()\n# obj.addBack(num)",
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"lang": "Python3",
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"code": "class SmallestInfiniteSet:\n\n def __init__(self):\n \n\n def popSmallest(self) -> int:\n \n\n def addBack(self, num: int) -> None:\n \n\n\n# Your SmallestInfiniteSet object will be instantiated and called as such:\n# obj = SmallestInfiniteSet()\n# param_1 = obj.popSmallest()\n# obj.addBack(num)",
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"lang": "C",
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"code": "\n\n\ntypedef struct {\n \n} SmallestInfiniteSet;\n\n\nSmallestInfiniteSet* smallestInfiniteSetCreate() {\n \n}\n\nint smallestInfiniteSetPopSmallest(SmallestInfiniteSet* obj) {\n \n}\n\nvoid smallestInfiniteSetAddBack(SmallestInfiniteSet* obj, int num) {\n \n}\n\nvoid smallestInfiniteSetFree(SmallestInfiniteSet* obj) {\n \n}\n\n/**\n * Your SmallestInfiniteSet struct will be instantiated and called as such:\n * SmallestInfiniteSet* obj = smallestInfiniteSetCreate();\n * int param_1 = smallestInfiniteSetPopSmallest(obj);\n \n * smallestInfiniteSetAddBack(obj, num);\n \n * smallestInfiniteSetFree(obj);\n*/",
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"lang": "C#",
"langSlug": "csharp",
"code": "public class SmallestInfiniteSet {\n\n public SmallestInfiniteSet() {\n \n }\n \n public int PopSmallest() {\n \n }\n \n public void AddBack(int num) {\n \n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * SmallestInfiniteSet obj = new SmallestInfiniteSet();\n * int param_1 = obj.PopSmallest();\n * obj.AddBack(num);\n */",
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"lang": "JavaScript",
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"code": "\nvar SmallestInfiniteSet = function() {\n \n};\n\n/**\n * @return {number}\n */\nSmallestInfiniteSet.prototype.popSmallest = function() {\n \n};\n\n/** \n * @param {number} num\n * @return {void}\n */\nSmallestInfiniteSet.prototype.addBack = function(num) {\n \n};\n\n/** \n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * var obj = new SmallestInfiniteSet()\n * var param_1 = obj.popSmallest()\n * obj.addBack(num)\n */",
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"lang": "Ruby",
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"code": "class SmallestInfiniteSet\n def initialize()\n \n end\n\n\n=begin\n :rtype: Integer\n=end\n def pop_smallest()\n \n end\n\n\n=begin\n :type num: Integer\n :rtype: Void\n=end\n def add_back(num)\n \n end\n\n\nend\n\n# Your SmallestInfiniteSet object will be instantiated and called as such:\n# obj = SmallestInfiniteSet.new()\n# param_1 = obj.pop_smallest()\n# obj.add_back(num)",
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"lang": "Swift",
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"code": "\nclass SmallestInfiniteSet {\n\n init() {\n \n }\n \n func popSmallest() -> Int {\n \n }\n \n func addBack(_ num: Int) {\n \n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * let obj = SmallestInfiniteSet()\n * let ret_1: Int = obj.popSmallest()\n * obj.addBack(num)\n */",
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"lang": "Go",
"langSlug": "golang",
"code": "type SmallestInfiniteSet struct {\n \n}\n\n\nfunc Constructor() SmallestInfiniteSet {\n \n}\n\n\nfunc (this *SmallestInfiniteSet) PopSmallest() int {\n \n}\n\n\nfunc (this *SmallestInfiniteSet) AddBack(num int) {\n \n}\n\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * obj := Constructor();\n * param_1 := obj.PopSmallest();\n * obj.AddBack(num);\n */",
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"lang": "Scala",
"langSlug": "scala",
"code": "class SmallestInfiniteSet() {\n\n def popSmallest(): Int = {\n \n }\n\n def addBack(num: Int) {\n \n }\n\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * var obj = new SmallestInfiniteSet()\n * var param_1 = obj.popSmallest()\n * obj.addBack(num)\n */",
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"lang": "Kotlin",
"langSlug": "kotlin",
"code": "class SmallestInfiniteSet() {\n\n fun popSmallest(): Int {\n \n }\n\n fun addBack(num: Int) {\n \n }\n\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * var obj = SmallestInfiniteSet()\n * var param_1 = obj.popSmallest()\n * obj.addBack(num)\n */",
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"lang": "Rust",
"langSlug": "rust",
"code": "struct SmallestInfiniteSet {\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 SmallestInfiniteSet {\n\n fn new() -> Self {\n \n }\n \n fn pop_smallest(&self) -> i32 {\n \n }\n \n fn add_back(&self, num: i32) {\n \n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * let obj = SmallestInfiniteSet::new();\n * let ret_1: i32 = obj.pop_smallest();\n * obj.add_back(num);\n */",
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"lang": "PHP",
"langSlug": "php",
"code": "class SmallestInfiniteSet {\n /**\n */\n function __construct() {\n \n }\n \n /**\n * @return Integer\n */\n function popSmallest() {\n \n }\n \n /**\n * @param Integer $num\n * @return NULL\n */\n function addBack($num) {\n \n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * $obj = SmallestInfiniteSet();\n * $ret_1 = $obj->popSmallest();\n * $obj->addBack($num);\n */",
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"lang": "TypeScript",
"langSlug": "typescript",
"code": "class SmallestInfiniteSet {\n constructor() {\n\n }\n\n popSmallest(): number {\n\n }\n\n addBack(num: number): void {\n\n }\n}\n\n/**\n * Your SmallestInfiniteSet object will be instantiated and called as such:\n * var obj = new SmallestInfiniteSet()\n * var param_1 = obj.popSmallest()\n * obj.addBack(num)\n */",
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"lang": "Racket",
"langSlug": "racket",
"code": "(define smallest-infinite-set%\n (class object%\n (super-new)\n \n (init-field)\n \n ; pop-smallest : -> exact-integer?\n (define/public (pop-smallest)\n\n )\n ; add-back : exact-integer? -> void?\n (define/public (add-back num)\n\n )))\n\n;; Your smallest-infinite-set% object will be instantiated and called as such:\n;; (define obj (new smallest-infinite-set%))\n;; (define param_1 (send obj pop-smallest))\n;; (send obj add-back num)",
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"lang": "Erlang",
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"code": "-spec smallest_infinite_set_init_() -> any().\nsmallest_infinite_set_init_() ->\n .\n\n-spec smallest_infinite_set_pop_smallest() -> integer().\nsmallest_infinite_set_pop_smallest() ->\n .\n\n-spec smallest_infinite_set_add_back(Num :: integer()) -> any().\nsmallest_infinite_set_add_back(Num) ->\n .\n\n\n%% Your functions will be called as such:\n%% smallest_infinite_set_init_(),\n%% Param_1 = smallest_infinite_set_pop_smallest(),\n%% smallest_infinite_set_add_back(Num),\n\n%% smallest_infinite_set_init_ will be called before every test case, in which you can do some necessary initializations.",
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"lang": "Elixir",
"langSlug": "elixir",
"code": "defmodule SmallestInfiniteSet do\n @spec init_() :: any\n def init_() do\n\n end\n\n @spec pop_smallest() :: integer\n def pop_smallest() do\n\n end\n\n @spec add_back(num :: integer) :: any\n def add_back(num) do\n\n end\nend\n\n# Your functions will be called as such:\n# SmallestInfiniteSet.init_()\n# param_1 = SmallestInfiniteSet.pop_smallest()\n# SmallestInfiniteSet.add_back(num)\n\n# SmallestInfiniteSet.init_ will be called before every test case, in which you can do some necessary initializations.",
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"hints": [
"Based on the constraints, what is the maximum element that can possibly be popped?",
"Maintain whether elements are in or not in the set. How many elements do we consider?"
],
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"sampleTestCase": "[\"SmallestInfiniteSet\",\"addBack\",\"popSmallest\",\"popSmallest\",\"popSmallest\",\"addBack\",\"popSmallest\",\"popSmallest\",\"popSmallest\"]\n[[],[2],[],[],[],[1],[],[],[]]",
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