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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
import scala.util.Sorting.quickSort
object Solution {
def longestConsecutive(nums: Array[Int]): Int = {
if (nums.isEmpty) {
return 0
}
quickSort(nums)
var max = Int.MinValue
var thisMax = 1
for (i <- 0 until nums.length - 1) {
if (nums(i + 1) == nums(i) + 1) {
thisMax += 1
} else if (nums(i + 1) != nums(i)) {
max = Math.max(max, thisMax)
thisMax = 1
}
}
Math.max(max, thisMax)
}
}