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Practice Longest Arithmetic Subsequence

Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.

Medium#1027
LeetCode Problem

Longest Arithmetic Subsequence

ArrayHash TableBinary SearchDynamic Programming

Problem Statement

Return the length of the longest arithmetic subsequence of nums. A subsequence retains the original order while optionally deleting elements. It is arithmetic when the difference between every pair of consecutive retained elements is the same.

Source: Longest Arithmetic Subsequence on LeetCode. Use the original task for its coding environment and submissions.

Examples

# Example 1

Input
nums = [3,6,9,12]
Output
4

# Example 2

Input
nums = [9,4,7,2,10]
Output
3

# Example 3

Input
nums = [20,1,15,3,10,5,8]
Output
4

Constraints

2 <= nums.length <= 1000
0 <= nums[i] <= 500

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