Longest Arithmetic Subsequence with Difference Constraint

Given a list of integers nums and an integer diff, return the length of the longest arithmetic subsequence where the difference between each consecutive numbers in the subsequence is diff.

Constraints

• 0 ≤ n ≤ 100,000 where n is the length of nums

https://binarysearch.com/problems/Longest-Arithmetic-Subsequence-with-Difference-Constraint

Examples

Example 1

Input

• nums = [-2, 0, 3, 6, 1, 9]
• diff = 3

Output

• answer = 4

Explanation

We can pick the subsequence [0, 3, 6, 9].

Example 2

Input

• nums = [9, 8, 7, 5, 3]
• diff = -2

Output

• answer = 4

Explanation

We can pick the subsequence [9, 7, 5, 3].

Solution