LeetCode 2407 Longest Increasing Subsequence II - Problem Statement

Find the longest strictly increasing subsequence where adjacent elements differ by at most $k$. For [4,2,1,4,3,4,5,8,15] with $k=3$, the answer is $5$ from subsequence [1,3,4,5,8].

Unlike standard LIS, the difference constraint requires a different approach. You'll use a segment tree for efficient range queries.

Example: [4,2,1,4,3,4,5,8,15], k=3 → 5. Longest subsequence with adjacent difference at most $k$.

Constraints: $1 \le$ nums.length $\le 10^5$, $1 \le$ nums[i], $k \le 10^5$.