[NEW] Add solution for Distinct Values Subsequences

## 🎯 Problem Information
- **Problem Name**: Distinct Values Subsequences
- **CSES Link**: https://cses.fi/problemset/task/3421
- **Category**: Sorting and Searching
- **Estimated Difficulty**: Medium

## 📋 Problem Description

<img width="672" height="675" alt="Image" src="https://github.com/user-attachments/assets/321f426a-bc5b-4bb8-8558-8c153728712c" />