一刷1650

Author: diguage

README.adoc

@@ -9420,6 +9420,13 @@ TIP: **公众号的微信号是: `jikerizhi`**。__因为众所周知的原因
 |Medium
 |树形DP套路，没有验证答案！
 
+|{counter:codes}
+|{leetcode_base_url}/lowest-common-ancestor-of-a-binary-tree-iii/[1650. Lowest Common Ancestor of a Binary Tree III^]
+|{source_base_url}/_1650_LowestCommonAncestorOfABinaryTreeIII.java[Java]
+|{doc_base_url}/1650-lowest-common-ancestor-of-a-binary-tree-iii.adoc[题解]
+|Medium
+|链表相交
+
 |{counter:codes}
 |{leetcode_base_url}/count-sub-islands/[1905. Count Sub Islands]
 |{source_base_url}/_1905_CountSubIslands.java[Java]

docs/1650-lowest-common-ancestor-of-a-binary-tree-iii.adoc

@@ -0,0 +1,77 @@
+[#1650-lowest-common-ancestor-of-a-binary-tree-iii]
+= 1650. Lowest Common Ancestor of a Binary Tree III
+
+https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iii/[LeetCode - 1650. Lowest Common Ancestor of a Binary Tree III ^]
+
+Given two nodes of a binary tree  `p` and  `q`, return **their lowest common ancestor (LCA)**.
+
+Each node will have a reference to its parent node. The definition for  `Node` is below:
+
+[{java_src_attr}]
+----
+class Node {
+    public int val;
+    public Node left;
+    public Node right;
+    public Node parent;
+}
+----
+
+According to the https://en.wikipedia.org/wiki/Lowest_common_ancestor[definition of LCA on Wikipedia^]: The lowest common ancestor of two nodes p and q in a tree T is the lowest node that has both p and q as descendants (where we allow a node to be a descendant of itself).
+
+ 
+**Example 1:**
+
+image::https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1600-1699/1650.Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree%20III/images/binarytree.png[]
+
+----
+**Input:** root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1
+**Output:** 3
+**Explanation:** The LCA of nodes 5 and 1 is 3.
+----
+
+**Example 2:**
+
+image::https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1600-1699/1650.Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree%20III/images/binarytree.png[]
+
+----
+**Input:** root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4
+**Output:** 5
+**Explanation:** The LCA of nodes 5 and 4 is 5 since a node can be a descendant of itself according to the LCA definition.
+----
+
+**Example 3:**
+
+----
+**Input:** root = [1,2], p = 1, q = 2
+**Output:** 1
+----
+
+**Constraints:**
+
+* The number of nodes in the tree is in the range  `[2, 10^5^]`.
+*  `-10^9^ <= Node.val <= 10^9^`
+* All  `Node.val` are **unique**.
+*  `p != q`
+*  `p` and  `q` exist in the tree.
+
+
+== 解题分析
+
+这道题披着树的外衣，里面确实一个链接相交的芯。
+
+[[src-1650]]
+[tabs]
+====
+一刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_1650_LowestCommonAncestorOfABinaryTreeIII.java[tag=answer]
+----
+--
+====
+
+
+

docs/index.adoc

@@ -2744,6 +2744,8 @@ include::1340-jump-game-v.adoc[leveloffset=+1]
 
 include::1644-lowest-common-ancestor-of-a-binary-tree-ii.adoc[leveloffset=+1]
 
+include::1650-lowest-common-ancestor-of-a-binary-tree-iii.adoc[leveloffset=+1]
+
 include::1905-count-sub-islands.adoc[leveloffset=+1]
 
 include::0000-00-note.adoc[leveloffset=+1]

logbook/202406.adoc

@@ -347,6 +347,11 @@
 |{doc_base_url}/0042-trapping-rain-water.adoc[题解]
 |巧用单调栈
 
+|{counter:codes}
+|{leetcode_base_url}/lowest-common-ancestor-of-a-binary-tree-iii/[1650. Lowest Common Ancestor of a Binary Tree III^]
+|{doc_base_url}/1650-lowest-common-ancestor-of-a-binary-tree-iii.adoc[题解]
+|链表相交
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

src/main/java/com/diguage/algo/leetcode/_1650_LowestCommonAncestorOfABinaryTreeIII.java

@@ -0,0 +1,60 @@
+package com.diguage.algo.leetcode;
+
+import java.util.Objects;
+
+public class _1650_LowestCommonAncestorOfABinaryTreeIII {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-07-26 20:00:58
+   */
+  public TreeNode lowestCommonAncestor(TreeNode p, TreeNode q) {
+    if (Objects.isNull(p) || Objects.isNull(q)) {
+      return null;
+    }
+    TreeNode a = p;
+    TreeNode b = q;
+    while (a != b) {
+      if (a == null) {
+        a = q;
+      } else {
+        a = a.parent;
+      }
+      if (b == null) {
+        b = p;
+      } else {
+        b = b.parent;
+      }
+    }
+    return a;
+  }
+  // end::answer[]
+
+  public class TreeNode {
+    public int val;
+    public TreeNode left;
+    public TreeNode right;
+    public TreeNode parent;
+
+    public TreeNode() {
+    }
+
+    public TreeNode(int x) {
+      val = x;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (this == o) return true;
+      if (o == null || getClass() != o.getClass()) return false;
+      TreeNode treeNode = (TreeNode) o;
+      return val == treeNode.val;
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(val);
+    }
+  }
+}