Longest Consecutive Sequence

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.

Example:
Given [100, 4, 200, 1, 3, 2],
The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4.

Your algorithm should run in O(n) complexity.

Interview Code Editor
1971 successful submissions.
Asked In:
  • Amazon
  • Google
Click here to jump start your coding interview preparation