리트코드 226번 Invert Binary Tree (python)

Problem

https://leetcode.com/problems/invert-binary-tree/description/

Solution

# Definition for a binary tree node.
from typing import Optional

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 dfs(node):
            if node is None:
                return
            
            node.left, node.right = node.right, node.left
            
            dfs(node.left)
            dfs(node.right)
            
            return 
        dfs(root)
        return root

leaf까지 left, right 스왑하면서 진행하면 된다.

Reference

파이썬 알고리즘 인터뷰 45번