三刷226

Author: diguage

docs/0226-invert-binary-tree.adoc

@@ -1,44 +1,56 @@
 [#0226-invert-binary-tree]
-= 226. Invert Binary Tree
+= 226. 翻转二叉树
 
-{leetcode}/problems/invert-binary-tree/[LeetCode - Invert Binary Tree^]
+https://leetcode.cn/problems/invert-binary-tree/[LeetCode - 226. 翻转二叉树^]
 
-Invert a binary tree.
+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。
 
-.Example:
-----
-Input:
-
-     4
-   /   \
-  2     7
- / \   / \
-1   3 6   9
-
-Output:
-     4
-   /   \
-  7     2
- / \   / \
-9   6 3   1
-----
+*示例 1：*
+
+image::images/0226-01.jpg[{image_attr}]
+
+....
+输入：root = [4,2,7,1,3,6,9]
+输出：[4,7,2,9,6,3,1]
+....
+
+*示例 2：*
 
-*Trivia:*
+image::images/0226-02.jpg[{image_attr}]
 
-This problem was inspired by https://twitter.com/mxcl/status/608682016205344768[this original tweet] by https://twitter.com/mxcl[Max Howell (@mxcl)^]:
+....
+输入：root = [2,1,3]
+输出：[2,3,1]
+....
 
-****
-Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.
-****
+*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+`
 
 
 == 思路分析
 
 D瓜哥也不会做这道题，现在可以说跟大神一个水平了，😆
 
+image::images/0226-10.png[{image_attr}]
+
+TIP: 现在D瓜哥可以顺利做出这道题，水平稳超大神，😁😁
+
 其实，思路很简单：就是递归地反转每棵树即可。
 
-image::images/0226-01.png[{image_attr}]
+image::images/0226-11.png[{image_attr}]
+
+动图演示如下：
+
+image::images/0226-12.gif[{image_attr}]
 
 [[src-0226]]
 [tabs]
@@ -60,9 +72,22 @@ include::{sourcedir}/_0226_InvertBinaryTree.java[tag=answer]
 include::{sourcedir}/_0226_InvertBinaryTree_2.java[tag=answer]
 ----
 --
+
+三刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0226_InvertBinaryTree_3.java[tag=answer]
+----
+--
 ====
 
+
 == 参考资料
 
-. https://leetcode.cn/problems/invert-binary-tree/solutions/415160/fan-zhuan-er-cha-shu-by-leetcode-solution/?envType=study-plan-v2&envId=selected-coding-interview[226. 翻转二叉树 - 官方题解^]
-. https://leetcode.cn/problems/invert-binary-tree/solutions/2361621/226-fan-zhuan-er-cha-shu-fen-zhi-qing-xi-tqlf/?envType=study-plan-v2&envId=selected-coding-interview[226. 翻转二叉树 - 深度优先搜索，清晰图解^]
+. https://leetcode.cn/problems/invert-binary-tree/solutions/2713610/shi-pin-shen-ru-li-jie-di-gui-pythonjava-zhqh/[226. 翻转二叉树 - 两种递归写法^]
+. https://leetcode.cn/problems/invert-binary-tree/solutions/73159/dong-hua-yan-shi-liang-chong-shi-xian-226-fan-zhua/[226. 翻转二叉树 - 动画演示 两种实现^]
+. https://leetcode.cn/problems/invert-binary-tree/solutions/415507/shou-hua-tu-jie-san-chong-xie-fa-di-gui-liang-chon/[226. 翻转二叉树 - 「手画图解」剖析Howell大神没写出的面试题^]
+. https://leetcode.cn/problems/invert-binary-tree/solutions/415160/fan-zhuan-er-cha-shu-by-leetcode-solution/[226. 翻转二叉树 - 官方题解^]
+. https://leetcode.cn/problems/invert-binary-tree/solutions/2361621/226-fan-zhuan-er-cha-shu-fen-zhi-qing-xi-tqlf/[226. 翻转二叉树 - 深度优先搜索，清晰图解^]

docs/images/0226-01.jpg

@@ -1789,6 +1789,11 @@ endif::[]
 |{doc_base_url}/0199-binary-tree-right-side-view.adoc[题解]
 |✅ 深度优先遍历。可以不用 `Map`，直接用 `List` 即可。要注意**先根遍历**和**中根遍历**的区别：先根遍历每层都是按顺序从上到下添加到 `List`；而中根遍历，每次都是最下层到，所以，要添加 `null` 占位符把 `List` 给撑起来，后续直接按照坐标设置。
 
+|{counter:codes2503}
+|{leetcode_base_url}/invert-binary-tree/[226. 翻转二叉树^]
+|{doc_base_url}/0226-invert-binary-tree.adoc[题解]
+|✅ 深度优先遍历或广度优先遍历。先递归再交换，或者先交换再递归。
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

docs/images/0226-02.jpg

@@ -0,0 +1,25 @@
+package com.diguage.algo.leetcode;
+
+import com.diguage.algo.util.TreeNode;
+
+import java.util.Objects;
+
+public class _0226_InvertBinaryTree_3 {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-10-26 20:41:17
+   */
+  public TreeNode invertTree(TreeNode root) {
+    if (Objects.isNull(root)) {
+      return root;
+    }
+    TreeNode left = invertTree(root.left);
+    TreeNode right = invertTree(root.right);
+    root.left = right; // 交换左右子树
+    root.right = left;
+    return root;
+  }
+  // end::answer[]
+
+}