/*
 * @lc app=leetcode.cn id=226 lang=javascript
 *
 * [226] 翻转二叉树
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {TreeNode}
 */
var invertTree = function(root) {
    if (!root) {
        return root
    }
    function reTree(node) {   
        let temp = node.left
        node.left = node.right
        node.right = temp
        if (node.left) {
            reTree(node.left)
        }
        if (node.right) {
            reTree(node.right)
        }
    }
    reTree(root)
    return root
};
// @lc code=end