300. Longest Increasing Subsequence #

Problem Statement: #

Given an integer array nums, return the length of the longest strictly increasing subsequence.

Example 1: #

Input: nums = [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.

Example 2: #

Input: nums = [0,1,0,3,2,3]
Output: 4

Example 3: #

Input: nums = [7,7,7,7,7,7,7]
Output: 1

Constraints: #

• 1 <= nums.length <= 2500
• -10⁴ <= nums[i] <= 10⁴

Follow up: Can you come up with an algorithm that runs in O(n log(n)) time complexity?

Solution: #

public int lengthOfLIS(int[] nums) {
  int[] lis = new int[nums.length];
  lis[0] = 1;
  for (int i = 1; i < lis.length; i++) {
  lis[i] = 1;
  for (int j = 0; j < i; j++) {
      if (nums[i] > nums[j])
      lis[i] = Math.max(lis[i], lis[j] + 1);
  }
  }
  int res = lis[0];
  for (int i : lis)
  res = Math.max(i, res);
  return res;
}

... #