LeetCode 热题100-38 翻转二叉树

万雅过往2024-08-29 20:02

翻转二叉树

给你一棵二叉树的根节点 root ，翻转这棵二叉树，并返回其根节点。

示例 1：

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输入：root = [4,2,7,1,3,6,9]
输出：[4,7,2,9,6,3,1]

示例 2：

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输入：root = [2,1,3]
输出：[2,3,1]

示例 3：

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输入：root = []
输出：[]

提示：

树中节点数目范围在 [0, 100] 内
-100 <= Node.val <= 100

python 复制代码

# 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]:
        def fun(root):
            if root == None: return root
            tmp = root.left
            root.left = root.right
            root.right = tmp
            fun(root.left)
            fun(root.right)
        fun(root)
        return root

感觉还是函数内的内置函数清晰一点，直接的递归感觉容易钻牛角尖...but还是写写吧

python 复制代码

# 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:return root
        root.right,root.left = self.invertTree(root.left),self.invertTree(root.right)
        return root