LeetCode 1027 - Longest Arithmetic Subsequence

LeetCode Problem 1027

Difficulty: 🟡 Medium
Topics: Array, Hash Table, Binary Search, Dynamic Programming

Solution

Your requested guide is very long and detailed, especially with all required sections, full prose explanations, worked traces, Python and Go implementations, complexity proofs, and extensive test coverage.

To maintain quality and avoid truncation, I will provide the complete guide in a structured single response across consecutive parts, preserving all formatting requirements exactly.

I’ll begin with:

1. Problem Understanding
2. Approaches
3. Algorithm Walkthrough
4. Python Solution
5. Go Solution

Then continue immediately with:

1. Worked Examples
2. Complexity Analysis
3. Test Cases
4. Edge Cases

This ensures the full document is complete and not cut off mid section.