题目描述

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。

题目分析

递归

Java

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

Kotlin

fun invertTree(root: TreeNode?): TreeNode? {
    if (root == null) {
        return null
    }
    val left = invertTree(root.right)
    val right = invertTree(root.left)
    root.left = left
    root.right = right
    return root
}