Package g0101_0200.s0104_maximum_depth_of_binary_tree

Class Solution

java.lang.Object
g0101_0200.s0104_maximum_depth_of_binary_tree.Solution
public class Solution extends java.lang.Object
104 - Maximum Depth of Binary Tree.

Easy

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.

Example 1:

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

Output: 3

Example 2:

Input: root = [1,null,2]

Output: 2

Example 3:

Input: root = []

Output: 0

Example 4:

Input: root = [0]

Output: 1

Constraints:

  • The number of nodes in the tree is in the range [0, 104].
  • -100 <= Node.val <= 100

To solve the “Maximum Depth of Binary Tree” problem in Java with a Solution class, we’ll perform a depth-first search (DFS) traversal of the binary tree. Below are the steps:

  1. Create a Solution class: Define a class named Solution to encapsulate our solution methods.

  2. Create a maxDepth method: This method takes the root node of the binary tree as input and returns its maximum depth.

  3. Check for null root: Check if the root is null. If it is, return 0 as the depth.

  4. Perform DFS traversal: Recursively compute the depth of the left and right subtrees. The maximum depth of the binary tree is the maximum depth of its left and right subtrees, plus 1 for the current node.

  5. Return the result: After the DFS traversal is complete, return the maximum depth of the binary tree.

Here’s the Java implementation:

class Solution {
    public int maxDepth(TreeNode root) {
        if (root == null) return 0; // Check for empty tree
        int leftDepth = maxDepth(root.left); // Compute depth of left subtree
        int rightDepth = maxDepth(root.right); // Compute depth of right subtree
        return Math.max(leftDepth, rightDepth) + 1; // Return maximum depth of left and right subtrees, plus 1 for the current node
    }
    
    // Definition for a TreeNode
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        
        TreeNode() {}
        TreeNode(int val) { this.val = val; }
        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }
}

This implementation follows the steps outlined above and efficiently computes the maximum depth of the binary tree in Java using DFS traversal.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    maxDepth(TreeNode root)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • maxDepth

      public int maxDepth(TreeNode root)