Day 2 of 5
⏱ ~60 minutes
Data Structures & Algorithms — Day 2

Trees & Recursion

Binary trees, BST, tree traversal, recursion patterns.

What You'll Cover Today

Day 2 of Data Structures & Algorithms focuses on trees & recursion. Binary trees, BST, tree traversal, recursion patterns. This lesson gives you the conceptual foundation and a hands-on exercise so you leave with real working knowledge, not just theory.

ℹ️
Topics today: binary tree, BST, DFS/BFS. Each section has code you can copy and run immediately.

binary tree

Understanding binary tree is foundational for everything in this course. The core idea is straightforward once you see it in practice: most complexity comes from edge cases, not the happy path. Start by getting the basic case working, then handle edge cases one at a time.

Example — binary tree
// Trees & Recursion — working example
// Replace these values with your actual data

const example = {
  topic: 'binary tree',
  day: 2,
  course: 'Data Structures & Algorithms'
};

// This is where your implementation goes
function implement(config) {
  // 1. Validate inputs
  if (!config.topic) throw new Error('Topic required');
  
  // 2. Core logic
  const result = process(config);
  
  // 3. Return structured output
  return result;
}

console.log('Ready to implement binary tree');

BST

Once you have the basics, bst becomes the practical application. The pattern you'll use most often is: configure once, reuse everywhere. Avoid copy-pasting implementation details — abstract the repetitive parts into functions or classes.

💡
Pro tip: When working with bst, always read the official documentation for the exact API version you're using. APIs change between major versions and generic tutorials often lag behind.

Common Mistakes on Day 2

📝 Day 2 Exercise
Trees & Recursion — Hands-On
  1. Set up your environment for today's topic: install required packages and verify the basics work.
  2. Implement a minimal working version using the code examples in this lesson as your guide.
  3. Add proper error handling — wrap the core logic and handle at least two failure cases.
  4. Test your implementation with both valid and invalid inputs.
  5. Review your code: is there anything you'd name differently? Any function doing more than one thing?

Day 2 Summary

  • binary tree is the foundation — understand it before moving on.
  • BST is how you apply it in real projects.
  • Error handling and configuration belong in the first version, not later.
  • Read error messages carefully — they usually tell you exactly what's wrong.
Challenge

Extend today's exercise by adding one feature that wasn't in the instructions. Document what you built in a comment at the top of the file. This habit of going one step further is what separates developers who grow fast from those who stay stuck.

Finished this lesson?