ほぼ日刊競プロ leetcode　226. Invert Binary Tree

226. Invert Binary Tree

Given the root of a binary tree, invert the tree, and return its root.

考えたこと

左と右のノードを入れ替えるだけで良い．

# 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 not root:
           return None
       ans = TreeNode(root.val)
       ans.right = self.invertTree(root.left)
       ans.left = self.invertTree(root.right)
       
       return ans