再次完成236

Author: diguage

docs/0235-lowest-common-ancestor-of-a-binary-search-tree.adoc

@@ -1,3 +1,4 @@
+[#0235-lowest-common-ancestor-of-a-binary-search-tree]
 = 235. Lowest Common Ancestor of a Binary Search Tree
 
 https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/[LeetCode - Lowest Common Ancestor of a Binary Search Tree]
@@ -62,6 +63,8 @@ image::images/0235-06.png[]
 include::{sourcedir}/_0235_LowestCommonAncestorOfABinarySearchTree.java[]
 ----
 
+作为这道题的延伸，继续看 xref:0236-lowest-common-ancestor-of-a-binary-tree.adoc[236. Lowest Common Ancestor of a Binary Tree]。
+
 == 参考资料
 
 . https://leetcode.cn/problems/lowest-common-ancestor-of-a-binary-search-tree/solutions/428633/er-cha-sou-suo-shu-de-zui-jin-gong-gong-zu-xian-26/[235. 二叉搜索树的最近公共祖先 - 官方题解^]

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

@@ -1,3 +1,5 @@
+
+[#0236-lowest-common-ancestor-of-a-binary-tree]
 = 236. Lowest Common Ancestor of a Binary Tree
 
 https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/[LeetCode - Lowest Common Ancestor of a Binary Tree]
@@ -8,9 +10,7 @@ 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
 
 思考题：如何按照"路径"的思路实现一遍？
 
-== 参考资料
-
-. https://en.wikipedia.org/wiki/Lowest_common_ancestor[Lowest common ancestor - Wikipedia]
+== 解题分析
 
 Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.
 
@@ -47,7 +47,60 @@ image::https://assets.leetcode.com/uploads/2018/12/14/binarytree.png[]
 * 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
+
+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：
+
+. 两个节点是一个树下的两个节点；
+. 一个节点就是另外一个节点的祖先节点；
+
+根据这两点，针对一棵树进行递归遍历，去寻找当前节点与两个指定节点相等的节点，找到就返回当前节点（也就是两个节点其中之一），找不到就返回 `null`。
+
+当左右子树都返回不为 `null` 时，那么当前节点就是两棵树的公共祖先节点。情况如下：
+
+image::images/0236-19.png[]
+
+
+
+image::images/0236-00.png[]
+
+image::images/0236-01.png[]
+
+image::images/0236-02.png[]
+
+image::images/0236-03.png[]
+
+image::images/0236-04.png[]
+
+image::images/0236-05.png[]
+
+image::images/0236-06.png[]
 
+image::images/0236-07.png[]
+
+image::images/0236-08.png[]
+
+image::images/0236-09.png[]
+
+image::images/0236-10.png[]
+
+image::images/0236-11.png[]
+
+image::images/0236-12.png[]
+
+image::images/0236-13.png[]
+
+image::images/0236-14.png[]
+
+image::images/0236-15.png[]
+
+image::images/0236-16.png[]
+
+image::images/0236-17.png[]
+
+image::images/0236-18.png[]
 
 
 [[src-0236]]
@@ -56,3 +109,15 @@ image::https://assets.leetcode.com/uploads/2018/12/14/binarytree.png[]
 include::{sourcedir}/_0236_LowestCommonAncestorOfABinaryTree.java[]
 ----
 
+[{java_src_attr}]
+----
+include::{sourcedir}/_0236_LowestCommonAncestorOfABinaryTree_2.java[]
+----
+
+== 参考资料
+
+. https://en.wikipedia.org/wiki/Lowest_common_ancestor[Lowest common ancestor - Wikipedia]
+. https://leetcode.cn/problems/lowest-common-ancestor-of-a-binary-tree/solutions/238552/er-cha-shu-de-zui-jin-gong-gong-zu-xian-by-leetc-2/[236. 二叉树的最近公共祖先 - 官方题解^]
+. https://leetcode.cn/problems/lowest-common-ancestor-of-a-binary-tree/solutions/240096/236-er-cha-shu-de-zui-jin-gong-gong-zu-xian-hou-xu/[236. 二叉树的最近公共祖先 - DFS ，清晰图解^]
+. https://leetcode.cn/problems/lowest-common-ancestor-of-a-binary-tree/solutions/2023872/fen-lei-tao-lun-luan-ru-ma-yi-ge-shi-pin-2r95/[236. 二叉树的最近公共祖先 - 本题最简单写法！^]
+