LeetCode 236: Lowest Common Ancestor of a Binary Tree | lecture 13 | Tree playlist | DSA

LeetCode 236: Lowest Common Ancestor of a Binary Tree (The Split Method!) Today we are tackling one of the most foundational tree problems in computer science: Lowest Common Ancestor (LCA). This question is a staple in technical interviews at companies like Microsoft, Amazon, and Apple because it beautifully tests your ability to return and bubble up values using recursion. Given two nodes in a binary tree, our job is to find the lowest node that has both of them as descendants. In this video, we will break down the recursive logic that allows us to find this exact "split point" efficiently in a single pass. 📌 What We Will Cover: 🎯 Understanding LCA: Visualizing what an ancestor is and identifying the exact moment two search paths intersect. 🧠 The Bottom-Up Postorder Approach: Why checking your left and right children before making a decision is the secret to this problem. 🔀 The 3 Return Scenarios: 1. If both left and right calls return a node, you are the LCA! 2. If only one side returns a node, pass that node up to your parent. 3. If both sides return null, return null. 💻 Line-by-Line Code Walkthrough: Writing clean, optimal code. 📈 Complexity Analysis: Why this approach achieved O(N) Time Complexity without needing extra space for parent pointers. 💬 Question of the Day: What happens to the logic if the problem changes from a standard Binary Tree to a Binary Search Tree (BST)? Does it get easier or harder? Let me know your thoughts in the comments below! If this video helped you conquer the LCA problem, show some love by hitting the Like button and Subscribing for more premium interview prep! #LeetCode #LowestCommonAncestor #LCA #BinaryTree #DataStructures #Algorithms #CodingInterview #FAANG #SoftwareEngineer #LearnToCode