二叉树222

222完全二叉树的节点个数

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def countNodes(self, root: Optional[TreeNode]) -> int:
        return self.getNodes(root)

    def getNodes(self, root) -> int:
        if root == None:
            return 0
        nodes_left = self.getNodes(root.left)
        nodes_right = self.getNodes(root.right)
        nodes_root = nodes_left + nodes_right + 1
        return nodes_root