{ "data": { "question": { "questionId": "41", "questionFrontendId": "41", "boundTopicId": null, "title": "First Missing Positive", "titleSlug": "first-missing-positive", "content": "

Given an unsorted integer array nums, return the smallest missing positive integer.

\n\n

You must implement an algorithm that runs in O(n) time and uses O(1) auxiliary space.

\n\n

 

\n

Example 1:

\n\n
\nInput: nums = [1,2,0]\nOutput: 3\nExplanation: The numbers in the range [1,2] are all in the array.\n
\n\n

Example 2:

\n\n
\nInput: nums = [3,4,-1,1]\nOutput: 2\nExplanation: 1 is in the array but 2 is missing.\n
\n\n

Example 3:

\n\n
\nInput: nums = [7,8,9,11,12]\nOutput: 1\nExplanation: The smallest positive integer 1 is missing.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": null, "translatedContent": null, "isPaidOnly": false, "difficulty": "Hard", "likes": 15416, "dislikes": 1729, "isLiked": null, "similarQuestions": "[{\"title\": \"Missing Number\", \"titleSlug\": \"missing-number\", \"difficulty\": \"Easy\", \"translatedTitle\": null}, {\"title\": \"Find the Duplicate Number\", \"titleSlug\": \"find-the-duplicate-number\", \"difficulty\": \"Medium\", \"translatedTitle\": null}, {\"title\": \"Find All Numbers Disappeared in an Array\", \"titleSlug\": \"find-all-numbers-disappeared-in-an-array\", \"difficulty\": \"Easy\", \"translatedTitle\": null}, {\"title\": \"Couples Holding Hands\", \"titleSlug\": \"couples-holding-hands\", \"difficulty\": \"Hard\", \"translatedTitle\": null}, {\"title\": \"Smallest Number in Infinite Set\", \"titleSlug\": \"smallest-number-in-infinite-set\", \"difficulty\": \"Medium\", \"translatedTitle\": null}, {\"title\": \"Maximum Number of Integers to Choose From a Range I\", \"titleSlug\": \"maximum-number-of-integers-to-choose-from-a-range-i\", \"difficulty\": \"Medium\", \"translatedTitle\": null}, {\"title\": \"Smallest Missing Non-negative Integer After Operations\", \"titleSlug\": \"smallest-missing-non-negative-integer-after-operations\", \"difficulty\": \"Medium\", \"translatedTitle\": null}, {\"title\": \"Maximum Number of Integers to Choose From a Range II\", \"titleSlug\": \"maximum-number-of-integers-to-choose-from-a-range-ii\", \"difficulty\": \"Medium\", \"translatedTitle\": null}]", "exampleTestcases": "[1,2,0]\n[3,4,-1,1]\n[7,8,9,11,12]", "categoryTitle": "Algorithms", "contributors": [], "topicTags": [ { "name": "Array", "slug": "array", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Hash Table", "slug": "hash-table", "translatedName": null, "__typename": "TopicTagNode" } ], "companyTagStats": null, "codeSnippets": [ { "lang": "C++", "langSlug": "cpp", "code": "class Solution {\npublic:\n int firstMissingPositive(vector& nums) {\n \n }\n};", "__typename": "CodeSnippetNode" }, { "lang": "Java", "langSlug": "java", "code": "class Solution {\n public int firstMissingPositive(int[] nums) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Python", "langSlug": "python", "code": "class Solution(object):\n def firstMissingPositive(self, nums):\n \"\"\"\n :type nums: List[int]\n :rtype: int\n \"\"\"\n ", "__typename": "CodeSnippetNode" }, { "lang": "Python3", "langSlug": "python3", "code": "class Solution:\n def firstMissingPositive(self, nums: List[int]) -> int:\n ", "__typename": "CodeSnippetNode" }, { "lang": "C", "langSlug": "c", "code": "int firstMissingPositive(int* nums, int numsSize) {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "C#", "langSlug": "csharp", "code": "public class Solution {\n public int FirstMissingPositive(int[] nums) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "JavaScript", "langSlug": "javascript", "code": "/**\n * @param {number[]} nums\n * @return {number}\n */\nvar firstMissingPositive = function(nums) {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "TypeScript", "langSlug": "typescript", "code": "function firstMissingPositive(nums: number[]): number {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "PHP", "langSlug": "php", "code": "class Solution {\n\n /**\n * @param Integer[] $nums\n * @return Integer\n */\n function firstMissingPositive($nums) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Swift", "langSlug": "swift", "code": "class Solution {\n func firstMissingPositive(_ nums: [Int]) -> Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Kotlin", "langSlug": "kotlin", "code": "class Solution {\n fun firstMissingPositive(nums: IntArray): Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Dart", "langSlug": "dart", "code": "class Solution {\n int firstMissingPositive(List nums) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Go", "langSlug": "golang", "code": "func firstMissingPositive(nums []int) int {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "Ruby", "langSlug": "ruby", "code": "# @param {Integer[]} nums\n# @return {Integer}\ndef first_missing_positive(nums)\n \nend", "__typename": "CodeSnippetNode" }, { "lang": "Scala", "langSlug": "scala", "code": "object Solution {\n def firstMissingPositive(nums: Array[Int]): Int = {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Rust", "langSlug": "rust", "code": "impl Solution {\n pub fn first_missing_positive(nums: Vec) -> i32 {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Racket", "langSlug": "racket", "code": "(define/contract (first-missing-positive nums)\n (-> (listof exact-integer?) exact-integer?)\n )", "__typename": "CodeSnippetNode" }, { "lang": "Erlang", "langSlug": "erlang", "code": "-spec first_missing_positive(Nums :: [integer()]) -> integer().\nfirst_missing_positive(Nums) ->\n .", "__typename": "CodeSnippetNode" }, { "lang": "Elixir", "langSlug": "elixir", "code": "defmodule Solution do\n @spec first_missing_positive(nums :: [integer]) :: integer\n def first_missing_positive(nums) do\n \n end\nend", "__typename": "CodeSnippetNode" } ], "stats": "{\"totalAccepted\": \"981.3K\", \"totalSubmission\": \"2.6M\", \"totalAcceptedRaw\": 981347, \"totalSubmissionRaw\": 2626654, \"acRate\": \"37.4%\"}", "hints": [ "Think about how you would solve the problem in non-constant space. Can you apply that logic to the existing space?", "We don't care about duplicates or non-positive integers", "Remember that O(2n) = O(n)" ], "solution": { "id": "681", "canSeeDetail": false, "paidOnly": true, "hasVideoSolution": false, "paidOnlyVideo": true, "__typename": "ArticleNode" }, "status": null, "sampleTestCase": "[1,2,0]", "metaData": "{\r\n \"name\": \"firstMissingPositive\",\r\n \"params\": [\r\n {\r\n \"name\": \"nums\",\r\n \"type\": \"integer[]\"\r\n }\r\n ],\r\n \"return\": {\r\n \"type\": \"integer\"\r\n }\r\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "enableTestMode": false, "enableDebugger": true, "envInfo": "{\"cpp\": [\"C++\", \"

Compiled with clang 11 using the latest C++ 20 standard.

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

Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.

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

Most standard library headers are already included automatically for your convenience.

\"], \"java\": [\"Java\", \"

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

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

Most standard library headers are already included automatically for your convenience.

\\r\\n

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

\"], \"python\": [\"Python\", \"

Python 2.7.12.

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

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

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

For Map/TreeMap data structure, you may use sortedcontainers library.

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

Note that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.

\"], \"c\": [\"C\", \"

Compiled with gcc 8.2 using the gnu11 standard.

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

Your code is compiled with level one optimization (-O1). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.

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

Most standard library headers are already included automatically for your convenience.

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

For hash table operations, you may use uthash. \\\"uthash.h\\\" is included by default. Below are some examples:

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

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

\\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
\\r\\n

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

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

\\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
\\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

\"], \"csharp\": [\"C#\", \"

C# 10 with .NET 6 runtime

\"], \"javascript\": [\"JavaScript\", \"

Node.js 16.13.2.

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

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

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

lodash.js library is included by default.

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

For Priority Queue / Queue data structures, you may use 5.3.0 version of datastructures-js/priority-queue and 4.2.1 version of datastructures-js/queue.

\"], \"ruby\": [\"Ruby\", \"

Ruby 3.1

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

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

\"], \"swift\": [\"Swift\", \"

Swift 5.5.2.

\"], \"golang\": [\"Go\", \"

Go 1.21

\\r\\n

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

\"], \"python3\": [\"Python3\", \"

Python 3.10.

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

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

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

For Map/TreeMap data structure, you may use sortedcontainers library.

\"], \"scala\": [\"Scala\", \"

Scala 2.13.7.

\"], \"kotlin\": [\"Kotlin\", \"

Kotlin 1.9.0.

\"], \"rust\": [\"Rust\", \"

Rust 1.58.1

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

Supports rand v0.6\\u00a0from crates.io

\"], \"php\": [\"PHP\", \"

PHP 8.1.

\\r\\n

With bcmath module

\"], \"typescript\": [\"Typescript\", \"

TypeScript 5.1.6, Node.js 16.13.2.

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

Your code is run with --harmony flag, enabling new ES2022 features.

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

lodash.js library is included by default.

\"], \"racket\": [\"Racket\", \"

Run with Racket 8.3.

\"], \"erlang\": [\"Erlang\", \"Erlang/OTP 25.0\"], \"elixir\": [\"Elixir\", \"Elixir 1.13.4 with Erlang/OTP 25.0\"], \"dart\": [\"Dart\", \"

Dart 2.17.3

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

Your code will be run directly without compiling

\"]}", "libraryUrl": null, "adminUrl": null, "challengeQuestion": null, "__typename": "QuestionNode" } } }