【leetcode】翻转二叉树

递归

# 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 invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        
        if root != None:
            self.invertTree(root.left)
            self.invertTree(root.right)
            tmp = root.right
            root.right = root.left
            root.left = tmp
        return root

迭代，有些麻烦，没有整理