LeetCode Maximum Depth of Binary Tree

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.

解题方法是使用递归，最大深度就是 左子树的最大深度 与 右子树最大深度 的最大值+1。

/**
 * 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;
            }
             if (root.left==null && root.right==null) {
                return 1;
            }
             return 1+Math.max(maxDepth(root.left), maxDepth(root.right));
    }
}