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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.

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 <= 105
  • -109 <= nums[i] <= 109

My solution​

/**
 * @param {number[]} nums
 * @return {number}
 */
var longestConsecutive = function(nums) {
    const set = new Set(nums);
    let sequence;
    let max = Number.MIN_SAFE_INTEGER;
    
    if (nums.length <= 1) {
        return nums.length;
    }
    
    for (const key of set.keys()) {
        let curr = +key;
        if (!set.has(key - 1)) {
            // console.log("curr", curr, set.has(curr))
            sequence = 0;
            while (set.has(curr)) {
                sequence++;
                curr++
            }
            // console.log(sequence)
            max = Math.max(sequence, max)
        }
        
    }
    return max
};