動機

寫的時候忘了這是交換…

Problem

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

 

Example 1:

Input: root = [4,2,7,1,3,6,9]Output: [4,7,2,9,6,3,1]

Example 2:

Input: root = [2,1,3]Output: [2,3,1]

Example 3:

Input: root = []Output: []

 

Constraints:

  • The number of nodes in the tree is in the range [0, 100].
  • -100 <= Node.val <= 100

Sol

這是交換，所以要照規矩來

class Solution:
    def invertTree(self, root: TreeNode) -> TreeNode:
        if root is not None:
            '''
            最一開始居然是寫
            root.left = root.right
            root.right = root.left
            笑死
            '''
            root.left, root.right = [root.right, root.left]
            self.invertTree(root.right)
            self.invertTree(root.left)
        return root