222 Count Complete Tree Nodes
使用递归自己调用自己的方法进行解决。
Python
# 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 countNodes(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if not root:
return 0
if not root.left and not root.right:
return 1
return self.countNodes(root.left) + self.countNodes(root.right) + 1