Leetcode 300. Longest Increasing Subsequence

Seawolf

Given an unsorted array of integers, find the length of longest increasing subsequence.

Example:

Input: [10,9,2,5,3,7,101,18]
Output: 4 
Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4. 
Note:

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?

class Solution:
    def lengthOfLIS(self, nums: List[int]) -> int:
        if nums == None or len(nums) == 0:
            return 0
        dp = [1 for _ in nums]
        res = 1
        for i in range(len(nums)):
            for j in range(i + 1, len(nums)):
                if nums[j] > nums[i]:
                    dp[j] = max(dp[j], dp[i] + 1)
                res = max(res, dp[j])
        return res