LeetCode in TypeScript
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:
0 <= nums.length <= 105-109 <= nums[i] <= 109
Solution
function longestConsecutive(nums: number[]): number {
let sset = new Set(nums)
let maxLen = 0
for (let num of sset) {
// check its start of the sequence
if (!sset.has(num - 1)) {
let len = 0
while (sset.has(num + len)) {
len += 1
}
maxLen = Math.max(maxLen, len)
}
}
return maxLen
}
export { longestConsecutive }