[226 Invert Binary Tree] #leetcode

226_0730.py

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def invertTree(self, root):
        """
        :type root: TreeNode
        :rtype: TreeNode
        """
        if root is None:
            return None
        
        root.right, root.left = self.invertTree(root.left), self.invertTree(root.right)
        return root

226_0731.java

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