【二叉树】226.翻转二叉树

题目

Python

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

Java

20240104重做

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        TreeNode originLeft = invertTree(root.left);
        TreeNode originRight = invertTree(root.right);
        root.left = originRight;
        root.right = originLeft;
        return root;
    }
}

20231205

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if (root == null || (root.left == null && root.right == null)) {
            return root;
        }
        TreeNode originR = invertTree(root.right);
        TreeNode originL = invertTree(root.left);
        root.left = originR;
        root.right = originL;
        return root;
    }
}