三刷236

Author: diguage

docs/0000-00-note.adoc

@@ -22,6 +22,8 @@ image::images/quick-sort-01.gif[{image_attr}]
 == TODO
 
 * [ ] https://leetcode.cn/problems/number-of-islands/solutions/211211/dao-yu-lei-wen-ti-de-tong-yong-jie-fa-dfs-bian-li-/[200. 岛屿数量 - 岛屿类问题的通用解法、DFS 遍历框架^]
+* [ ] 魔改的二分查找
+* [ ] 买卖股票
 
 == 解题范式
 

docs/0236-lowest-common-ancestor-of-a-binary-tree.adoc

@@ -4,23 +4,14 @@
 
 {leetcode}/problems/lowest-common-ancestor-of-a-binary-tree/[LeetCode - Lowest Common Ancestor of a Binary Tree^]
 
-image::images/0236-1.png[{image_attr}]
-
-D瓜哥的思路：先找出一条从根节点到某个节点的路径；然后从这条路径上以此去寻找另外一个节点。找到这返回此节点。
-
-思考题：如何按照"路径"的思路实现一遍？
-
-== 解题分析
-
 Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.
 
 According to the https://en.wikipedia.org/wiki/Lowest_common_ancestor[definition of LCA on Wikipedia^]: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow *a node to be a descendant of itself*).”
 
 Given the following binary tree:  root = [3,5,1,6,2,0,8,null,null,7,4]
 
-image::https://assets.leetcode.com/uploads/2018/12/14/binarytree.png[{image_attr}]
+image::images/0236-1.png[{image_attr}]
 
-
 *Example 1:*
 
 [subs="verbatim,quotes,macros"]
@@ -47,8 +38,13 @@ image::https://assets.leetcode.com/uploads/2018/12/14/binarytree.png[{image_attr
 * All of the nodes' values will be unique.
 * p and q are different and both values will exist in the binary tree.
 
+
 == 思路分析
 
+D瓜哥的思路：先找出一条从根节点到某个节点的路径；然后从这条路径上以此去寻找另外一个节点。找到这返回此节点。
+
+思考题：如何按照"路径"的思路实现一遍？
+
 这道题是 xref:0235-lowest-common-ancestor-of-a-binary-search-tree.adoc[235. Lowest Common Ancestor of a Binary Search Tree] 的延伸。但是，解题思路略有不同，本体的解题思路也可用于前者。
 
 有两种情况：
@@ -104,15 +100,35 @@ image::images/0236-18.png[{image_attr}]
 
 
 [[src-0236]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0236_LowestCommonAncestorOfABinaryTree.java[tag=answer]
 ----
+--
 
+二刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0236_LowestCommonAncestorOfABinaryTree_2.java[tag=answer]
 ----
+--
+
+三刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0236_LowestCommonAncestorOfABinaryTree_3.java[tag=answer]
+----
+--
+====
 
 == 参考资料
 

logbook/202406.adoc

@@ -565,6 +565,11 @@
 |{doc_base_url}/0704-binary-search.adoc[题解]
 |二分查找
 
+|{counter:codes}
+|{leetcode_base_url}/lowest-common-ancestor-of-a-binary-tree/[236. Lowest Common Ancestor of a Binary Tree^]
+|{doc_base_url}/0236-lowest-common-ancestor-of-a-binary-tree.adoc[题解]
+|想清楚怎么判断是否为公共祖先。
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

src/main/java/com/diguage/algo/leetcode/_0236_LowestCommonAncestorOfABinaryTree_2.java

@@ -42,6 +42,9 @@ public class _0236_LowestCommonAncestorOfABinaryTree_2 {
   // tag::answer[]
   /**
    * 参考 左程云《程序员代码面试指南》的解法
+   *
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-06-24 21:08:59
    */
   public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
     if (root == null || root == p || root == q) {

src/main/java/com/diguage/algo/leetcode/_0236_LowestCommonAncestorOfABinaryTree_3.java

@@ -0,0 +1,20 @@
+package com.diguage.algo.leetcode;
+
+import com.diguage.algo.util.TreeNode;
+
+public class _0236_LowestCommonAncestorOfABinaryTree_3 {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-09-14 21:42:37
+   */
+  public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+    if (root == null || root.val == p.val || root.val == q.val) {
+      return root;
+    }
+    TreeNode left = lowestCommonAncestor(root.left, p, q);
+    TreeNode right = lowestCommonAncestor(root.right, p, q);
+    return left == null ? (right == null ? null : right) : left;
+  }
+  // end::answer[]
+}