LeetCode-in-All

128. Longest Consecutive Sequence

Medium

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: 4

Explanation: 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:

Solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var longestConsecutive = function(nums) {
    if (nums.length === 0) {
        return 0
    }
    nums.sort((a, b) => a - b)
    let max = Number.MIN_SAFE_INTEGER
    let thsMax = 1
    for (let i = 0; i < nums.length - 1; i++) {
        if (nums[i + 1] === nums[i] + 1) {
            thsMax += 1
            continue
        }
        if (nums[i + 1] === nums[i]) {
            continue
        }
        max = Math.max(max, thsMax)
        thsMax = 1 // NOSONAR
    }
    return Math.max(max, thsMax)
};

export { longestConsecutive }