"content":"<p>Design a stack-like data structure to push elements to the stack and pop the most frequent element from the stack.</p>\n\n<p>Implement the <code>FreqStack</code> class:</p>\n\n<ul>\n\t<li><code>FreqStack()</code> constructs an empty frequency stack.</li>\n\t<li><code>void push(int val)</code> pushes an integer <code>val</code> onto the top of the stack.</li>\n\t<li><code>int pop()</code> removes and returns the most frequent element in the stack.\n\t<ul>\n\t\t<li>If there is a tie for the most frequent element, the element closest to the stack's top is removed and returned.</li>\n\t</ul>\n\t</li>\n</ul>\n\n<p> </p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input</strong>\n["FreqStack", "push", "push", "push", "push", "push", "push", "pop", "pop", "pop", "pop"]\n[[], [5], [7], [5], [7], [4], [5], [], [], [], []]\n<strong>Output</strong>\n[null, null, null, null, null, null, null, 5, 7, 5, 4]\n\n<strong>Explanation</strong>\nFreqStack freqStack = new FreqStack();\nfreqStack.push(5); // The stack is [5]\nfreqStack.push(7); // The stack is [5,7]\nfreqStack.push(5); // The stack is [5,7,5]\nfreqStack.push(7); // The stack is [5,7,5,7]\nfreqStack.push(4); // The stack is [5,7,5,7,4]\nfreqStack.push(5); // The stack is [5,7,5,7,4,5]\nfreqStack.pop(); // return 5, as 5 is the most frequent. The stack becomes [5,7,5,7,4].\nfreqStack.pop(); // return 7, as 5 and 7 is the most frequent, but 7 is closest to the top. The stack becomes [5,7,5,4].\nfreqStack.pop(); // return 5, as 5 is the most frequent. The stack becomes [5,7,4].\nfreqStack.pop(); // return 4, as 4, 5 and 7 is the most frequent, but 4 is closest to the top. The stack becomes [5,7].\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>0 <= val <= 10<sup>9</sup></code></li>\n\t<li>At most <code>2 * 10<sup>4</sup></code> calls will be made to <code>push</code> and <code>pop</code>.</li>\n\t<li>It is guaranteed that there will be at least one element in the stack before calling <code>pop</code>.</li>\n</ul>\n",
"code":"class FreqStack {\npublic:\n FreqStack() {\n \n }\n \n void push(int val) {\n \n }\n \n int pop() {\n \n }\n};\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * FreqStack* obj = new FreqStack();\n * obj->push(val);\n * int param_2 = obj->pop();\n */",
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{
"lang":"Java",
"langSlug":"java",
"code":"class FreqStack {\n\n public FreqStack() {\n \n }\n \n public void push(int val) {\n \n }\n \n public int pop() {\n \n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * FreqStack obj = new FreqStack();\n * obj.push(val);\n * int param_2 = obj.pop();\n */",
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{
"lang":"Python",
"langSlug":"python",
"code":"class FreqStack(object):\n\n def __init__(self):\n \n\n def push(self, val):\n \"\"\"\n :type val: int\n :rtype: None\n \"\"\"\n \n\n def pop(self):\n \"\"\"\n :rtype: int\n \"\"\"\n \n\n\n# Your FreqStack object will be instantiated and called as such:\n# obj = FreqStack()\n# obj.push(val)\n# param_2 = obj.pop()",
"__typename":"CodeSnippetNode"
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{
"lang":"Python3",
"langSlug":"python3",
"code":"class FreqStack:\n\n def __init__(self):\n \n\n def push(self, val: int) -> None:\n \n\n def pop(self) -> int:\n \n\n\n# Your FreqStack object will be instantiated and called as such:\n# obj = FreqStack()\n# obj.push(val)\n# param_2 = obj.pop()",
"__typename":"CodeSnippetNode"
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{
"lang":"C",
"langSlug":"c",
"code":"\n\n\ntypedef struct {\n \n} FreqStack;\n\n\nFreqStack* freqStackCreate() {\n \n}\n\nvoid freqStackPush(FreqStack* obj, int val) {\n \n}\n\nint freqStackPop(FreqStack* obj) {\n \n}\n\nvoid freqStackFree(FreqStack* obj) {\n \n}\n\n/**\n * Your FreqStack struct will be instantiated and called as such:\n * FreqStack* obj = freqStackCreate();\n * freqStackPush(obj, val);\n \n * int param_2 = freqStackPop(obj);\n \n * freqStackFree(obj);\n*/",
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{
"lang":"C#",
"langSlug":"csharp",
"code":"public class FreqStack {\n\n public FreqStack() {\n \n }\n \n public void Push(int val) {\n \n }\n \n public int Pop() {\n \n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * FreqStack obj = new FreqStack();\n * obj.Push(val);\n * int param_2 = obj.Pop();\n */",
"__typename":"CodeSnippetNode"
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{
"lang":"JavaScript",
"langSlug":"javascript",
"code":"\nvar FreqStack = function() {\n \n};\n\n/** \n * @param {number} val\n * @return {void}\n */\nFreqStack.prototype.push = function(val) {\n \n};\n\n/**\n * @return {number}\n */\nFreqStack.prototype.pop = function() {\n \n};\n\n/** \n * Your FreqStack object will be instantiated and called as such:\n * var obj = new FreqStack()\n * obj.push(val)\n * var param_2 = obj.pop()\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Ruby",
"langSlug":"ruby",
"code":"class FreqStack\n def initialize()\n \n end\n\n\n=begin\n :type val: Integer\n :rtype: Void\n=end\n def push(val)\n \n end\n\n\n=begin\n :rtype: Integer\n=end\n def pop()\n \n end\n\n\nend\n\n# Your FreqStack object will be instantiated and called as such:\n# obj = FreqStack.new()\n# obj.push(val)\n# param_2 = obj.pop()",
"__typename":"CodeSnippetNode"
},
{
"lang":"Swift",
"langSlug":"swift",
"code":"\nclass FreqStack {\n\n init() {\n \n }\n \n func push(_ val: Int) {\n \n }\n \n func pop() -> Int {\n \n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * let obj = FreqStack()\n * obj.push(val)\n * let ret_2: Int = obj.pop()\n */",
"__typename":"CodeSnippetNode"
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{
"lang":"Go",
"langSlug":"golang",
"code":"type FreqStack struct {\n \n}\n\n\nfunc Constructor() FreqStack {\n \n}\n\n\nfunc (this *FreqStack) Push(val int) {\n \n}\n\n\nfunc (this *FreqStack) Pop() int {\n \n}\n\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * obj := Constructor();\n * obj.Push(val);\n * param_2 := obj.Pop();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Scala",
"langSlug":"scala",
"code":"class FreqStack() {\n\n def push(`val`: Int) {\n \n }\n\n def pop(): Int = {\n \n }\n\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * var obj = new FreqStack()\n * obj.push(`val`)\n * var param_2 = obj.pop()\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Kotlin",
"langSlug":"kotlin",
"code":"class FreqStack() {\n\n fun push(`val`: Int) {\n \n }\n\n fun pop(): Int {\n \n }\n\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * var obj = FreqStack()\n * obj.push(`val`)\n * var param_2 = obj.pop()\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Rust",
"langSlug":"rust",
"code":"struct FreqStack {\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 FreqStack {\n\n fn new() -> Self {\n \n }\n \n fn push(&self, val: i32) {\n \n }\n \n fn pop(&self) -> i32 {\n \n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * let obj = FreqStack::new();\n * obj.push(val);\n * let ret_2: i32 = obj.pop();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"PHP",
"langSlug":"php",
"code":"class FreqStack {\n /**\n */\n function __construct() {\n \n }\n \n /**\n * @param Integer $val\n * @return NULL\n */\n function push($val) {\n \n }\n \n /**\n * @return Integer\n */\n function pop() {\n \n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * $obj = FreqStack();\n * $obj->push($val);\n * $ret_2 = $obj->pop();\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"TypeScript",
"langSlug":"typescript",
"code":"class FreqStack {\n constructor() {\n\n }\n\n push(val: number): void {\n\n }\n\n pop(): number {\n\n }\n}\n\n/**\n * Your FreqStack object will be instantiated and called as such:\n * var obj = new FreqStack()\n * obj.push(val)\n * var param_2 = obj.pop()\n */",
"__typename":"CodeSnippetNode"
},
{
"lang":"Racket",
"langSlug":"racket",
"code":"(define freq-stack%\n (class object%\n (super-new)\n (init-field)\n \n ; push : exact-integer? -> void?\n (define/public (push val)\n\n )\n ; pop : -> exact-integer?\n (define/public (pop)\n\n )))\n\n;; Your freq-stack% object will be instantiated and called as such:\n;; (define obj (new freq-stack%))\n;; (send obj push val)\n;; (define param_2 (send obj pop))",
"__typename":"CodeSnippetNode"
},
{
"lang":"Erlang",
"langSlug":"erlang",
"code":"-spec freq_stack_init_() -> any().\nfreq_stack_init_() ->\n .\n\n-spec freq_stack_push(Val :: integer()) -> any().\nfreq_stack_push(Val) ->\n .\n\n-spec freq_stack_pop() -> integer().\nfreq_stack_pop() ->\n .\n\n\n%% Your functions will be called as such:\n%% freq_stack_init_(),\n%% freq_stack_push(Val),\n%% Param_2 = freq_stack_pop(),\n\n%% freq_stack_init_ will be called before every test case, in which you can do some necessary initializations.",
"__typename":"CodeSnippetNode"
},
{
"lang":"Elixir",
"langSlug":"elixir",
"code":"defmodule FreqStack do\n @spec init_() :: any\n def init_() do\n\n end\n\n @spec push(val :: integer) :: any\n def push(val) do\n\n end\n\n @spec pop() :: integer\n def pop() do\n\n end\nend\n\n# Your functions will be called as such:\n# FreqStack.init_()\n# FreqStack.push(val)\n# param_2 = FreqStack.pop()\n\n# FreqStack.init_ will be called before every test case, in which you can do some necessary initializations.",
"envInfo":"{\"cpp\": [\"C++\", \"<p>Compiled with <code> clang 11 </code> using the latest C++ 17 standard.</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 17 </code>. Java 8 features such as lambda expressions and stream API can be used. </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 2.7.12</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\\\">will not be maintained past 2020</a>. For the latest Python, please choose Python3 instead.</p>\"], \"c\": [\"C\", \"<p>Compiled with <code>gcc 8.2</code> using the gnu99 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level one optimization (<code>-O1</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://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-9\\\" target=\\\"_blank\\\">C# 10 with .NET 6 runtime</a></p>\\r\\n\\r\\n<p>Your code is compiled with debug flag enabled (<code>/debug</code>).</p>\"], \"javascript\": [\"JavaScript\", \"<p><code>Node.js 16.13.2</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 <a href=\\\"https://github.com/datastructures-js/priority-queue\\\" target=\\\"_blank\\\">datastructures-js/priority-queue</a> and <a href=\\\"https:
