LeetCode - Longest Consecutive Sequence - JAVA - Solution

Welcome to this video on solving the Leetcode Longest Consecutive Sequence problem with O(n) time complexity.

In this problem, we are given an unsorted array of integers and we need to find the length of the longest consecutive sequence of integers.

One approach to solving this problem would be to sort the array and then loop through it, keeping track of the current longest sequence and updating it whenever we find a longer one. However, this would have a time complexity of O(n * log n) due to the sorting step.

Instead, one other approach to this problem is we put the array into the hash set and check the element is the first element of the sequence by checking the previous element exists. If the current element is the first element in the sequence we search for the next element and keep track of the count.

This approach has a time complexity of O(n) because we only need to loop through the array once and perform constant-time operations on the hash set.

I hope this helps give you an understanding of how to solve the Leetcode Longest Consecutive Sequence problem with O(n) time complexity. Thanks for watching!