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Hello **Programmers/Coders,** Today we are going to share ** solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python**. At Each Problem with Successful submission with

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In this post, you will find the solution for the **Longest Consecutive Sequence** **in C++, Java & Python-LeetCode problem**. We are providing the **correct and tested solutions** to coding problems present on **LeetCode**. If you are not able to solve any problem, then you can take help from our Blog/website.

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** Link for the Problem** – Longest Consecutive Sequence– LeetCode Problem

Longest Consecutive Sequence– LeetCode Problem

**Problem:**

Given an unsorted array of integers `nums`

, return *the length of the longest consecutive elements sequence.*

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

time.

**Example 1:**

Input:nums = [100,4,200,1,3,2]Output:4Explanation:The longest consecutive elements sequence is`[1, 2, 3, 4]`

. Therefore its length is 4.

**Example 2:**

Input:nums = [0,3,7,2,5,8,4,6,0,1]Output:9

**Constraints:**

`0 <= nums.length <= 10`

^{5}`-10`

^{9}<= nums[i] <= 10^{9}

Longest Consecutive Sequence– LeetCode Solutions

Longest Consecutive Sequence Solution in C++:

class Solution { public: int longestConsecutive(vector& nums) { int ans = 0; unordered_set seen{begin(nums), end(nums)}; for (int num : nums) { // num is the start of a sequence if (seen.count(num - 1)) continue; int length = 1; while (seen.count(++num)) ++length; ans = max(ans, length); } return ans; } };

Longest Consecutive Sequence Solution in Java:

class Solution { public int longestConsecutive(int[] nums) { int ans = 0; Setseen = new HashSet<>(); for (final int num : nums) seen.add(num); for (int num : nums) { // num is the start of a sequence if (seen.contains(num - 1)) continue; int length = 1; while (seen.contains(++num)) ++length; ans = Math.max(ans, length); } return ans; } }

Longest Consecutive Sequence Solution in Python:

class Solution: def longestConsecutive(self, nums: List[int]) -> int: ans = 0 seen = set(nums) for num in nums: if num - 1 in seen: continue length = 0 while num in seen: num += 1 length += 1 ans = max(ans, length) return ans