<p>Given an unsorted array of integers <code>nums</code>, return <em>the length of the longest consecutive elements sequence.</em></p>

<p>You must write an algorithm that runs in&nbsp;<code>O(n)</code>&nbsp;time.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [100,4,200,1,3,2]
<strong>Output:</strong> 4
<strong>Explanation:</strong> The longest consecutive elements sequence is <code>[1, 2, 3, 4]</code>. Therefore its length is 4.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,3,7,2,5,8,4,6,0,1]
<strong>Output:</strong> 9
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution:
    def longestConsecutive(self, nums: List[int]) -> int:
        my_dict = {i: False for i in nums}

        nums_set = {i: False for i in nums}

        max_length = 0

        for num in nums:
            if nums_set.get(num) == True:
                continue

            curr_len = 1
            nums_set[num] = True

            prev_num = num-1
            while nums_set.get(prev_num)==False:
                nums_set[prev_num] = True
                curr_len += 1
                prev_num -= 1

            next_num = num+1
            while nums_set.get(next_num)==False:
                nums_set[next_num] = True
                curr_len += 1
                next_num += 1

            max_length = max(max_length, curr_len)

        return max_length
            

40030