Maximum Depth of Binary Tree

Q:

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Solution:

Recursive call.

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