PROBLEM7.md

PROBLEM 7: Longest Consecutive Sequence

Problem Statement

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.

Concepts Covered

• HashSet for fast lookup
• Greedy Expansion

Examples

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

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

Starter Code

def longest_consecutive(nums: list[int]) -> int:
    # Implement your solution here
    pass