Given an unsorted array of integers, find the length of longest increasing subsequence.
[10,9,2,5,3,7,101,18]Output: 4 Explanation: The longest increasing subsequence is
[2,3,7,101], therefore the length is
- There may be more than one LIS combination, it is only necessary for you to return the length.
- Your algorithm should run in O(n2) complexity.
Follow up: Could you improve it to O(n log n) time complexity?