{ "data": { "question": { "questionId": "128", "questionFrontendId": "128", "boundTopicId": null, "title": "Longest Consecutive Sequence", "titleSlug": "longest-consecutive-sequence", "content": "

Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.

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You must write an algorithm that runs in O(n) time.

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Example 1:

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\nInput: nums = [100,4,200,1,3,2]\nOutput: 4\nExplanation: The longest consecutive elements sequence is [1, 2, 3, 4]. Therefore its length is 4.\n
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Example 2:

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\nInput: nums = [0,3,7,2,5,8,4,6,0,1]\nOutput: 9\n
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Constraints:

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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.

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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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Python 2.7.12.

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

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C# 10 with .NET 6 runtime

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Node.js 16.13.2.

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Ruby 3.1

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Python 3.10.

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