三刷142

Author: diguage

docs/0142-linked-list-cycle-ii.adoc

@@ -88,15 +88,35 @@ image::images/0142-15.png[{image_attr}]
 
 
 [[src-0142]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0142_LinkedListCycleII.java[tag=answer]
 ----
+--
 
+二刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0142_LinkedListCycleII_2.java[tag=answer]
 ----
+--
+
+三刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0142_LinkedListCycleII_3.java[tag=answer]
+----
+--
+====
 
 
 == 思考题

logbook/202406.adoc

@@ -550,6 +550,11 @@
 |{doc_base_url}/0387-first-unique-character-in-a-string.adoc[题解]
 |哈希+字符串
 
+|{counter:codes}
+|{leetcode_base_url}/linked-list-cycle-ii/[142. Linked List Cycle II^]
+|{doc_base_url}/0142-linked-list-cycle-ii.adoc[题解]
+|快慢指针
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

src/main/java/com/diguage/algo/leetcode/_0142_LinkedListCycleII_2.java

@@ -14,7 +14,8 @@ public class _0142_LinkedListCycleII_2 {
   // tag::answer[]
 
   /**
-   *
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-07-02 21:08:43
    */
   public ListNode detectCycle(ListNode head) {
     if (head == null || head.next == null) {

src/main/java/com/diguage/algo/leetcode/_0142_LinkedListCycleII_3.java

@@ -0,0 +1,37 @@
+package com.diguage.algo.leetcode;
+
+import com.diguage.algo.util.ListNode;
+
+public class _0142_LinkedListCycleII_3 {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-09-14 17:02:00
+   */
+  public ListNode detectCycle(ListNode head) {
+    ListNode slow = head;
+    ListNode fast = head;
+    while (fast != null && fast.next != null) {
+      slow = slow.next;
+      fast = fast.next;
+      fast = fast.next;
+      if (slow == fast) {
+        break;
+      }
+    }
+    if (fast == null || fast.next == null) {
+      return null;
+    }
+    slow = head;
+    while (slow != fast) {
+      slow = slow.next;
+      fast = fast.next;
+      if (slow == fast) {
+        break;
+      }
+    }
+    return slow;
+  }
+  // end::answer[]
+}