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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 {
const set = new Set(nums)
let max = 0
for (const num of nums) {
if (set.has(num + 1)) continue
let counter = 1,
current = num
while (set.has(--current)) counter++
max = Math.max(counter, max)
}
return max
}
export { longestConsecutive }