226.翻转二叉树

链接: https://leetcode.cn/problems/invert-binary-tree/

代码随想录的解: https://www.programmercarl.com/0226.翻转二叉树.html

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func invertTree(root *TreeNode) *TreeNode {
	if root == nil {
		return nil
	}
	var dfs func(node *TreeNode)
	dfs = func(node *TreeNode) {
		node.Left, node.Right = node.Right, node.Left
		if node.Left != nil {
			dfs(node.Left)
		}
		if node.Right != nil {
			dfs(node.Right)
		}
	}
	dfs(root)
	return root
}