题解 | #二叉树的镜像#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param pRoot TreeNode类 
# @return TreeNode类
#
class Solution:
    def Mirror(self , pRoot: TreeNode) -> TreeNode:
        # write code here
        if not pRoot:
            return 
        root_left = pRoot.left
        root_right  =pRoot.right
        pRoot.left = self.Mirror(root_right)
        pRoot.right = self.Mirror(root_left)
        return pRoot

DP的思想，可以划分为原问题的子问题，根节点的左节点为self.Mirror(root_right)，根节点的右节点为self.Mirror(root_left)