What is the Maximum Depth of Binary Tree pattern?

The Maximum Depth of Binary Tree is a common coding interview pattern in Depth First Search problems. It provides a structured approach to solving related algorithm challenges efficiently.

When should I use Maximum Depth of Binary Tree?

Use the Maximum Depth of Binary Tree pattern when you encounter problems matching its characteristics. Check the "When to Use" and "Clues" sections in the lesson for specific indicators.

Is Maximum Depth of Binary Tree asked in FAANG interviews?

Yes, Maximum Depth of Binary Tree is an essential pattern commonly tested in FAANG and top tech company technical interviews.

Browse Curriculum

Depth-First Search

Easy

Maximum Depth of Binary Tree

Find the maximum depth (height) of a binary tree.

10 min read

Solve on LeetCode

Examples

Input:root = [3,9,20,null,null,15,7]

Output:3

Explain:

The tree has nodes 3 -> (9, 20). 20 -> (15, 7). The longest path is 3->20->15 (length 3).

Input:root = [1,null,2]

Output:2

Problem Understanding

Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Algorithm Strategy (Bottom-Up)

We use Post-order DFS (Bottom-Up) to solve this.

Base Case: If the node is null, its depth is 0.
Recursive Step:
- Ask the Left Child: "What is your max depth?"
- Ask the Right Child: "What is your max depth?"
Calculation: My Depth = max(left_depth, right_depth) + 1.

Interactive Visualization

Step 1 / 1

Empty Heap

Initializing...

Custom Input

Visualize how the depth values bubble up from the leaves to the root.

Stop Guessing, Start Mastering.

Build the FAANG intuition. Master this pattern with optimized implementations, visual dry runs, and our curated collection of high-yield problems.