{ "data": { "question": { "questionId": "27", "questionFrontendId": "27", "boundTopicId": null, "title": "Remove Element", "titleSlug": "remove-element", "content": "

Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val.

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Consider the number of elements in nums which are not equal to val be k, to get accepted, you need to do the following things:

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Custom Judge:

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The judge will test your solution with the following code:

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\nint[] nums = [...]; // Input array\nint val = ...; // Value to remove\nint[] expectedNums = [...]; // The expected answer with correct length.\n                            // It is sorted with no values equaling val.\n\nint k = removeElement(nums, val); // Calls your implementation\n\nassert k == expectedNums.length;\nsort(nums, 0, k); // Sort the first k elements of nums\nfor (int i = 0; i < actualLength; i++) {\n    assert nums[i] == expectedNums[i];\n}\n
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If all assertions pass, then your solution will be accepted.

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Example 1:

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\nInput: nums = [3,2,2,3], val = 3\nOutput: 2, nums = [2,2,_,_]\nExplanation: Your function should return k = 2, with the first two elements of nums being 2.\nIt does not matter what you leave beyond the returned k (hence they are underscores).\n
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Example 2:

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\nInput: nums = [0,1,2,2,3,0,4,2], val = 2\nOutput: 5, nums = [0,1,4,0,3,_,_,_]\nExplanation: Your function should return k = 5, with the first five elements of nums containing 0, 0, 1, 3, and 4.\nNote that the five elements can be returned in any order.\nIt does not matter what you leave beyond the returned k (hence they are underscores).\n
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Constraints:

\n\n\n", "translatedTitle": null, "translatedContent": null, "isPaidOnly": false, "difficulty": "Easy", "likes": 1634, "dislikes": 2421, "isLiked": null, "similarQuestions": "[{\"title\": \"Remove Duplicates from Sorted Array\", \"titleSlug\": \"remove-duplicates-from-sorted-array\", \"difficulty\": \"Easy\", \"translatedTitle\": null}, {\"title\": \"Remove Linked List Elements\", \"titleSlug\": \"remove-linked-list-elements\", \"difficulty\": \"Easy\", \"translatedTitle\": null}, {\"title\": \"Move Zeroes\", \"titleSlug\": \"move-zeroes\", \"difficulty\": \"Easy\", \"translatedTitle\": null}]", "exampleTestcases": "[3,2,2,3]\n3\n[0,1,2,2,3,0,4,2]\n2", "categoryTitle": "Algorithms", "contributors": [], "topicTags": [ { "name": "Array", "slug": "array", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Two Pointers", "slug": "two-pointers", "translatedName": null, "__typename": "TopicTagNode" } ], "companyTagStats": null, "codeSnippets": [ { "lang": "C++", "langSlug": "cpp", "code": "class Solution {\npublic:\n int removeElement(vector& nums, int val) {\n \n }\n};", "__typename": "CodeSnippetNode" }, { "lang": "Java", "langSlug": "java", "code": "class Solution {\n public int removeElement(int[] nums, int val) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Python", "langSlug": "python", "code": "class Solution(object):\n def removeElement(self, nums, val):\n \"\"\"\n :type nums: List[int]\n :type val: int\n :rtype: int\n \"\"\"\n ", "__typename": "CodeSnippetNode" }, { "lang": "Python3", "langSlug": "python3", "code": "class Solution:\n def removeElement(self, nums: List[int], val: int) -> int:\n ", "__typename": "CodeSnippetNode" }, { "lang": "C", "langSlug": "c", "code": "int removeElement(int* nums, int numsSize, int val) {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "C#", "langSlug": "csharp", "code": "public class Solution {\n public int RemoveElement(int[] nums, int val) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "JavaScript", "langSlug": "javascript", "code": "/**\n * @param {number[]} nums\n * @param {number} val\n * @return {number}\n */\nvar removeElement = function(nums, val) {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "TypeScript", "langSlug": "typescript", "code": "function removeElement(nums: number[], val: number): number {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "PHP", "langSlug": "php", "code": "class Solution {\n\n /**\n * @param Integer[] $nums\n * @param Integer $val\n * @return Integer\n */\n function removeElement(&$nums, $val) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Swift", "langSlug": "swift", "code": "class Solution {\n func removeElement(_ nums: inout [Int], _ val: Int) -> Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Kotlin", "langSlug": "kotlin", "code": "class Solution {\n fun removeElement(nums: IntArray, `val`: Int): Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Dart", "langSlug": "dart", "code": "class Solution {\n int removeElement(List nums, int val) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Go", "langSlug": "golang", "code": "func removeElement(nums []int, val int) int {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "Ruby", "langSlug": "ruby", "code": "# @param {Integer[]} nums\n# @param {Integer} val\n# @return {Integer}\ndef remove_element(nums, val)\n \nend", "__typename": "CodeSnippetNode" }, { "lang": "Scala", "langSlug": "scala", "code": "object Solution {\n def removeElement(nums: Array[Int], `val`: Int): Int = {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Rust", "langSlug": "rust", "code": "impl Solution {\n pub fn remove_element(nums: &mut Vec, val: i32) -> i32 {\n \n }\n}", "__typename": "CodeSnippetNode" } ], "stats": "{\"totalAccepted\": \"2.4M\", \"totalSubmission\": \"4.3M\", \"totalAcceptedRaw\": 2368579, \"totalSubmissionRaw\": 4286369, \"acRate\": \"55.3%\"}", "hints": [ "The problem statement clearly asks us to modify the array in-place and it also says that the element beyond the new length of the array can be anything. Given an element, we need to remove all the occurrences of it from the array. We don't technically need to remove that element per-say, right?", "We can move all the occurrences of this element to the end of the array. Use two pointers!\r\n
", "Yet another direction of thought is to consider the elements to be removed as non-existent. In a single pass, if we keep copying the visible elements in-place, that should also solve this problem for us." ], "solution": { "id": "22", "canSeeDetail": false, "paidOnly": true, "hasVideoSolution": true, "paidOnlyVideo": true, "__typename": "ArticleNode" }, "status": null, "sampleTestCase": "[3,2,2,3]\n3", "metaData": "{\r\n \"name\": \"removeElement\",\r\n \"params\": [\r\n {\r\n \"name\": \"nums\",\r\n \"type\": \"integer[]\"\r\n },\r\n {\r\n \"name\": \"val\",\r\n \"type\": \"integer\"\r\n }\r\n ],\r\n \"return\": {\r\n \"type\": \"integer\"\r\n },\r\n \"output\": {\r\n \"paramindex\": 0,\r\n \"size\": \"ret\"\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.

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

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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.

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

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

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

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

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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.

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

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

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

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

C# 10 with .NET 6 runtime

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

Node.js 16.13.2.

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

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lodash.js library is included by default.

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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.

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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.

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

Go 1.21

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

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

Python 3.10.

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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.

\\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

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Supports rand v0.6\\u00a0from crates.io

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

PHP 8.1.

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With bcmath module

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

TypeScript 5.1.6, Node.js 16.13.2.

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

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lodash.js library is included by default.

\"], \"dart\": [\"Dart\", \"

Dart 2.17.3

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Your code will be run directly without compiling

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