Скачать или смотреть LeetCode | Unique Length 3 Palindromic Subsequences | C++ | Golang | Rust

In this video, I solve the LeetCode problem “Unique Length-3 Palindromic Subsequences” using C++, Rust, and Go (Golang).
This problem asks us to count the number of distinct palindromic subsequences of length 3 (pattern: a _ a).
I explain the full logic, optimized approach, and language-specific implementations.

⏱ Timestamps

00:00 – Problem Breakdown & Logic
12:07 – Dry Run of Algorithm
21:03 – Faster lookup logic
23:03 – C++ Implementation
27:04 – Golang Implementation
33:09 – Rust Implementation

You’ll learn:

How palindromic subsequences of form x_y_x work

Frequency-based counting strategy

Set-based uniqueness logic

Optimized linear-time O(N) solution

Implementations in C++, Rust, and Go

Perfect for anyone preparing for coding interviews or improving problem-solving skills.


⚠ Quick correction: @40:55
I accidentally said 576 instead of 676 (26×26).
This is what happens when you solve LeetCode before breakfast 😭☕
Space complexity is still O(1)!