1027. Longest Arithmetic Subsequence

Given an array nums of integers, return the length of the longest arithmetic subsequence in nums. Note that: - A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements. - A sequence seq is arithmetic if seq[i + 1] - seq[i] are all the same value (for 0 <= i < seq.length - 1). Example 1: Input: nums