题目给你一棵二叉树的根节点root翻转这棵二叉树并返回其根节点。示例 1输入root [4,2,7,1,3,6,9]输出[4,7,2,9,6,3,1]示例 2输入root [2,1,3]输出[2,3,1]示例 3输入root []输出[]提示树中节点数目范围在[0, 100]内-100 Node.val 100题解/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val val; * this.left left; * this.right right; * } * } */ class Solution { public TreeNode invertTree(TreeNode root) { if(root null) return null; //交换当前节点左右子树 TreeNode tmp root.right; root.right root.left; root.left tmp; //递归交换当前节点的左子树 invertTree(root.left); //递归交换当前节点的右子树 invertTree(root.right); return root; } }