{ "data": { "question": { "questionId": "2587", "questionFrontendId": "2502", "boundTopicId": null, "title": "Design Memory Allocator", "titleSlug": "design-memory-allocator", "content": "

You are given an integer n representing the size of a 0-indexed memory array. All memory units are initially free.

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You have a memory allocator with the following functionalities:

\n\n
    \n\t
  1. Allocate a block of size consecutive free memory units and assign it the id mID.
  2. \n\t
  3. Free all memory units with the given id mID.
  4. \n
\n\n

Note that:

\n\n\n\n

Implement the Allocator class:

\n\n\n\n

 

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Example 1:

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\nInput\n["Allocator", "allocate", "allocate", "allocate", "free", "allocate", "allocate", "allocate", "free", "allocate", "free"]\n[[10], [1, 1], [1, 2], [1, 3], [2], [3, 4], [1, 1], [1, 1], [1], [10, 2], [7]]\nOutput\n[null, 0, 1, 2, 1, 3, 1, 6, 3, -1, 0]\n\nExplanation\nAllocator loc = new Allocator(10); // Initialize a memory array of size 10. All memory units are initially free.\nloc.allocate(1, 1); // The leftmost block's first index is 0. The memory array becomes [1,_,_,_,_,_,_,_,_,_]. We return 0.\nloc.allocate(1, 2); // The leftmost block's first index is 1. The memory array becomes [1,2,_,_,_,_,_,_,_,_]. We return 1.\nloc.allocate(1, 3); // The leftmost block's first index is 2. The memory array becomes [1,2,3,_,_,_,_,_,_,_]. We return 2.\nloc.free(2); // Free all memory units with mID 2. The memory array becomes [1,_, 3,_,_,_,_,_,_,_]. We return 1 since there is only 1 unit with mID 2.\nloc.allocate(3, 4); // The leftmost block's first index is 3. The memory array becomes [1,_,3,4,4,4,_,_,_,_]. We return 3.\nloc.allocate(1, 1); // The leftmost block's first index is 1. The memory array becomes [1,1,3,4,4,4,_,_,_,_]. We return 1.\nloc.allocate(1, 1); // The leftmost block's first index is 6. The memory array becomes [1,1,3,4,4,4,1,_,_,_]. We return 6.\nloc.free(1); // Free all memory units with mID 1. The memory array becomes [_,_,3,4,4,4,_,_,_,_]. We return 3 since there are 3 units with mID 1.\nloc.allocate(10, 2); // We can not find any free block with 10 consecutive free memory units, so we return -1.\nloc.free(7); // Free all memory units with mID 7. The memory array remains the same since there is no memory unit with mID 7. We return 0.\n
\n\n

 

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Constraints:

\n\n\n", "translatedTitle": null, "translatedContent": null, "isPaidOnly": false, "difficulty": "Medium", "likes": 258, "dislikes": 78, "isLiked": null, "similarQuestions": "[]", "exampleTestcases": "[\"Allocator\",\"allocate\",\"allocate\",\"allocate\",\"free\",\"allocate\",\"allocate\",\"allocate\",\"free\",\"allocate\",\"free\"]\n[[10],[1,1],[1,2],[1,3],[2],[3,4],[1,1],[1,1],[1],[10,2],[7]]", "categoryTitle": "Algorithms", "contributors": [], "topicTags": [ { "name": "Array", "slug": "array", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Hash Table", "slug": "hash-table", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Design", "slug": "design", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Simulation", "slug": "simulation", "translatedName": null, "__typename": "TopicTagNode" } ], "companyTagStats": null, "codeSnippets": [ { "lang": "C++", "langSlug": "cpp", "code": "class Allocator {\npublic:\n Allocator(int n) {\n \n }\n \n int allocate(int size, int mID) {\n \n }\n \n int free(int mID) {\n \n }\n};\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * Allocator* obj = new Allocator(n);\n * int param_1 = obj->allocate(size,mID);\n * int param_2 = obj->free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Java", "langSlug": "java", "code": "class Allocator {\n\n public Allocator(int n) {\n \n }\n \n public int allocate(int size, int mID) {\n \n }\n \n public int free(int mID) {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * Allocator obj = new Allocator(n);\n * int param_1 = obj.allocate(size,mID);\n * int param_2 = obj.free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Python", "langSlug": "python", "code": "class Allocator(object):\n\n def __init__(self, n):\n \"\"\"\n :type n: int\n \"\"\"\n \n\n def allocate(self, size, mID):\n \"\"\"\n :type size: int\n :type mID: int\n :rtype: int\n \"\"\"\n \n\n def free(self, mID):\n \"\"\"\n :type mID: int\n :rtype: int\n \"\"\"\n \n\n\n# Your Allocator object will be instantiated and called as such:\n# obj = Allocator(n)\n# param_1 = obj.allocate(size,mID)\n# param_2 = obj.free(mID)", "__typename": "CodeSnippetNode" }, { "lang": "Python3", "langSlug": "python3", "code": "class Allocator:\n\n def __init__(self, n: int):\n \n\n def allocate(self, size: int, mID: int) -> int:\n \n\n def free(self, mID: int) -> int:\n \n\n\n# Your Allocator object will be instantiated and called as such:\n# obj = Allocator(n)\n# param_1 = obj.allocate(size,mID)\n# param_2 = obj.free(mID)", "__typename": "CodeSnippetNode" }, { "lang": "C", "langSlug": "c", "code": "\n\n\ntypedef struct {\n \n} Allocator;\n\n\nAllocator* allocatorCreate(int n) {\n \n}\n\nint allocatorAllocate(Allocator* obj, int size, int mID) {\n \n}\n\nint allocatorFree(Allocator* obj, int mID) {\n \n}\n\nvoid allocatorFree(Allocator* obj) {\n \n}\n\n/**\n * Your Allocator struct will be instantiated and called as such:\n * Allocator* obj = allocatorCreate(n);\n * int param_1 = allocatorAllocate(obj, size, mID);\n \n * int param_2 = allocatorFree(obj, mID);\n \n * allocatorFree(obj);\n*/", "__typename": "CodeSnippetNode" }, { "lang": "C#", "langSlug": "csharp", "code": "public class Allocator {\n\n public Allocator(int n) {\n \n }\n \n public int Allocate(int size, int mID) {\n \n }\n \n public int Free(int mID) {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * Allocator obj = new Allocator(n);\n * int param_1 = obj.Allocate(size,mID);\n * int param_2 = obj.Free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "JavaScript", "langSlug": "javascript", "code": "/**\n * @param {number} n\n */\nvar Allocator = function(n) {\n \n};\n\n/** \n * @param {number} size \n * @param {number} mID\n * @return {number}\n */\nAllocator.prototype.allocate = function(size, mID) {\n \n};\n\n/** \n * @param {number} mID\n * @return {number}\n */\nAllocator.prototype.free = function(mID) {\n \n};\n\n/** \n * Your Allocator object will be instantiated and called as such:\n * var obj = new Allocator(n)\n * var param_1 = obj.allocate(size,mID)\n * var param_2 = obj.free(mID)\n */", "__typename": "CodeSnippetNode" }, { "lang": "TypeScript", "langSlug": "typescript", "code": "class Allocator {\n constructor(n: number) {\n \n }\n\n allocate(size: number, mID: number): number {\n \n }\n\n free(mID: number): number {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * var obj = new Allocator(n)\n * var param_1 = obj.allocate(size,mID)\n * var param_2 = obj.free(mID)\n */", "__typename": "CodeSnippetNode" }, { "lang": "PHP", "langSlug": "php", "code": "class Allocator {\n /**\n * @param Integer $n\n */\n function __construct($n) {\n \n }\n \n /**\n * @param Integer $size\n * @param Integer $mID\n * @return Integer\n */\n function allocate($size, $mID) {\n \n }\n \n /**\n * @param Integer $mID\n * @return Integer\n */\n function free($mID) {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * $obj = Allocator($n);\n * $ret_1 = $obj->allocate($size, $mID);\n * $ret_2 = $obj->free($mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Swift", "langSlug": "swift", "code": "\nclass Allocator {\n\n init(_ n: Int) {\n \n }\n \n func allocate(_ size: Int, _ mID: Int) -> Int {\n \n }\n \n func free(_ mID: Int) -> Int {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * let obj = Allocator(n)\n * let ret_1: Int = obj.allocate(size, mID)\n * let ret_2: Int = obj.free(mID)\n */", "__typename": "CodeSnippetNode" }, { "lang": "Kotlin", "langSlug": "kotlin", "code": "class Allocator(n: Int) {\n\n fun allocate(size: Int, mID: Int): Int {\n \n }\n\n fun free(mID: Int): Int {\n \n }\n\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * var obj = Allocator(n)\n * var param_1 = obj.allocate(size,mID)\n * var param_2 = obj.free(mID)\n */", "__typename": "CodeSnippetNode" }, { "lang": "Dart", "langSlug": "dart", "code": "class Allocator {\n\n Allocator(int n) {\n \n }\n \n int allocate(int size, int mID) {\n \n }\n \n int free(int mID) {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * Allocator obj = Allocator(n);\n * int param1 = obj.allocate(size,mID);\n * int param2 = obj.free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Go", "langSlug": "golang", "code": "type Allocator struct {\n \n}\n\n\nfunc Constructor(n int) Allocator {\n \n}\n\n\nfunc (this *Allocator) Allocate(size int, mID int) int {\n \n}\n\n\nfunc (this *Allocator) Free(mID int) int {\n \n}\n\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * obj := Constructor(n);\n * param_1 := obj.Allocate(size,mID);\n * param_2 := obj.Free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Ruby", "langSlug": "ruby", "code": "class Allocator\n\n=begin\n :type n: Integer\n=end\n def initialize(n)\n \n end\n\n\n=begin\n :type size: Integer\n :type m_id: Integer\n :rtype: Integer\n=end\n def allocate(size, m_id)\n \n end\n\n\n=begin\n :type m_id: Integer\n :rtype: Integer\n=end\n def free(m_id)\n \n end\n\n\nend\n\n# Your Allocator object will be instantiated and called as such:\n# obj = Allocator.new(n)\n# param_1 = obj.allocate(size, m_id)\n# param_2 = obj.free(m_id)", "__typename": "CodeSnippetNode" }, { "lang": "Scala", "langSlug": "scala", "code": "class Allocator(_n: Int) {\n\n def allocate(size: Int, mID: Int): Int = {\n \n }\n\n def free(mID: Int): Int = {\n \n }\n\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * var obj = new Allocator(n)\n * var param_1 = obj.allocate(size,mID)\n * var param_2 = obj.free(mID)\n */", "__typename": "CodeSnippetNode" }, { "lang": "Rust", "langSlug": "rust", "code": "struct Allocator {\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 Allocator {\n\n fn new(n: i32) -> Self {\n \n }\n \n fn allocate(&self, size: i32, m_id: i32) -> i32 {\n \n }\n \n fn free(&self, m_id: i32) -> i32 {\n \n }\n}\n\n/**\n * Your Allocator object will be instantiated and called as such:\n * let obj = Allocator::new(n);\n * let ret_1: i32 = obj.allocate(size, mID);\n * let ret_2: i32 = obj.free(mID);\n */", "__typename": "CodeSnippetNode" }, { "lang": "Racket", "langSlug": "racket", "code": "(define allocator%\n (class object%\n (super-new)\n \n ; n : exact-integer?\n (init-field\n n)\n \n ; allocate : exact-integer? exact-integer? -> exact-integer?\n (define/public (allocate size m-id)\n )\n ; free : exact-integer? -> exact-integer?\n (define/public (free m-id)\n )))\n\n;; Your allocator% object will be instantiated and called as such:\n;; (define obj (new allocator% [n n]))\n;; (define param_1 (send obj allocate size m-id))\n;; 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Most standard library headers are already included automatically for your convenience.

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OpenJDK 17. Java 8 features such as lambda expressions and stream API can be used.

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Includes Pair class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.

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Python 2.7.12.

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Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.

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Compiled with gcc 8.2 using the gnu11 standard.

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1. Adding an item to a hash.\\r\\n

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\\r\\n

\\r\\n\\r\\n

2. Looking up an item in a hash:\\r\\n

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\\r\\n

\\r\\n\\r\\n

3. Deleting an item in a hash:\\r\\n

\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n    HASH_DEL(users, user);  \\r\\n}\\r\\n
\\r\\n

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C# 10 with .NET 6 runtime

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Node.js 16.13.2.

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Your code is run with --harmony flag, enabling new ES6 features.

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Ruby 3.1

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Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms

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Swift 5.5.2.

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Go 1.21

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Support https://godoc.org/github.com/emirpasic/gods@v1.18.1 library.

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Python 3.10.

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Scala 2.13.7.

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Kotlin 1.9.0.

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Rust 1.58.1

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Supports rand v0.6\\u00a0from crates.io

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PHP 8.1.

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With bcmath module

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TypeScript 5.1.6, Node.js 16.13.2.

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Dart 2.17.3

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Your code will be run directly without compiling

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