Decision Tree Path Challenge – Understanding Arrays as Binary Trees in C#

C# Coding Challenges – From Easy to Mind-Bending Problems

Welcome to my C# Coding Challenges series — where I take real algorithm problems from platforms like HackerRank, LeetCode, and ByteCode, and explain every single step, line by line, until it truly makes sense.

In this episode, we tackle one of the most conceptually tricky challenges:

“Find the path from the root to the lowest-value leaf in a binary tree represented as an array.”

This problem may look simple at first, but it’s not. It combines:

Tree logic (parent/child relationships)

Index math (2i+1 / 2i+2 formulas)

Reverse path reconstruction (bottom-up traversal)

Clean C# structuring (static methods, small helpers, stack usage)

By the end, you’ll fully understand how a tree can live inside an array — and how to navigate it using pure math, without any Node class.

💡 What You’ll Learn

How arrays can represent balanced binary trees

How to find leaf nodes efficiently

How to trace parent relationships using index arithmetic

How to build clean and testable methods in C#

How to think algorithmically through every step

⚙️ Tools Used

C# (.NET 9)

xUnit for tests

Graphviz & Mermaid for tree visualization

GitHub for code and documentation
🐙 https://github.com/weslley182/DecisionTreePathChallenge
🌐 https://wesleydevcamp.wordpress.com/2025/10/15/decision-tree-path-challenge/

🏁 Challenge Summary

Given a tree stored in an array, find the lowest-value leaf and return the root-to-leaf path as “L” and “R”.

Example:

[0, 4, 2, 5, 0, 9, 7, 9, -4, 2, -5, 3, 9, 1, -11]
→ Output: "RRR"

🔥 Difficulty: Hard / Tricky Conceptually

This one separates those who can just code from those who truly understand structure and indexing.

📺 Tags

#CSharp #CodingChallenge #BinaryTree #Algorithms #CleanCode #DataStructures #DevContent #DotNet #LearningPath

Видео Decision Tree Path Challenge – Understanding Arrays as Binary Trees in C# канала Wesley Machado