📚 4.翻转二叉树

💻 代码实现

/**
 * @url https://leetcode.cn/problems/invert-binary-tree/description/
 */

import { rootCertificates } from "tls"

class TreeNode {
    val: number
    left: TreeNode | null
    right: TreeNode | null
    constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
        this.val = val === undefined ? 0 : val
        this.left = left === undefined ? null : left
        this.right = right === undefined ? null : right
    }
}

function invertTree(root: TreeNode | null): TreeNode | null {
    if (!root) return null
    if (root) {
        let p = root.left
        root.left = root.right
        root.right = p
        invertTree(root.left)
        invertTree(root.right)
    }
    return root
}