104. Maximum Depth Of Binary Tree¶

Difficulty: Easy

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

Constraints:

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

Solution¶

/**
 * 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 {
    static int height;
    public int maxDepth(TreeNode root) {
        height = 0;
        dfs(root);
        return height;
    }
    static int dfs(TreeNode root) {
        if (root == null) return 0;
        int left = dfs(root.left);
        int right = dfs(root.right);
        height = Math.max(height, Math.max(left, right) + 1);
        return Math.max(left, right) + 1;
    }
}

Complexity Analysis¶

Time Complexity: O(?)
Space Complexity: O(?)

Approach¶

Detailed explanation of the approach will be added here