cixuuz

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def invertTree(self, root):
        """

cixuuz

public class Solution {
    public int maxDepth(TreeNode root) {
        if (root == null) {
            return 0;
        } 
        
        return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
    }
}