树-222. 完全二叉树的节点个数- 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

        stack = list()
        count = 1
        stack.append(root)
        while stack:
            tmp = stack.pop(0)
            if tmp.left:
                count += 1
                stack.append(tmp.left)
            if tmp.right:
                count += 1
                stack.append(tmp.right)

        return count

来源：CSDN

作者：宋建国

链接：https://blog.csdn.net/hot7732788/article/details/104646733