In this post, we are going to solve the 104. Maximum Depth of Binary Tree problem of Leetcode. This problem 104. Maximum Depth of Binary Tree is a Leetcode easy level problem. Let’s see the code, 104. Maximum Depth of Binary Tree – Leetcode Solution.

Problem

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

Constraints

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

Now, let’s see the code of 104. Maximum Depth of Binary Tree – Leetcode Solution.

Maximum Depth of Binary Tree – Leetcode Solution

104. Maximum Depth of Binary Tree – Solution in Java

/**
 * Definition for a binary tree node.
 * 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;
 *     }
 * }
 */
class Solution {
    public int maxDepth(TreeNode root) {
        if(root == null) return 0;
        int leftDepth = maxDepth(root.left);
        int rightDepth = maxDepth(root.right);
        return Math.max(leftDepth,rightDepth) + 1;
    }
}

104. Maximum Depth of Binary Tree – Solution in C++

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
int maxDepth(TreeNode* root) {
        if(!root) return 0;
        int maxLeft = maxDepth(root->left);
        int maxRight = maxDepth(root->right);
        return max(maxLeft, maxRight)+1;
    }
};

104. Maximum Depth of Binary Tree – Solution in Python

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        def dfs(root, depth):
            if not root: return depth
            return max(dfs(root.left, depth + 1), dfs(root.right, depth + 1))
                       
        return dfs(root, 0)
        

Note: This problem 104. Maximum Depth of Binary Tree is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.