From d850713638583fe3aab28ddd71495f12959883a4 Mon Sep 17 00:00:00 2001
From: Joshua <47053655+Joshua-Lu@users.noreply.github.com>
Date: Thu, 13 May 2021 23:17:10 +0800
Subject: [PATCH] =?UTF-8?q?Update=200142.=E7=8E=AF=E5=BD=A2=E9=93=BE?=
 =?UTF-8?q?=E8=A1=A8II.md?=
MIME-Version: 1.0
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添加 0142.环形链表II.md Java版本
---
 problems/0142.环形链表II.md | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/problems/0142.环形链表II.md b/problems/0142.环形链表II.md
index 9622affc..7556b854 100644
--- a/problems/0142.环形链表II.md
+++ b/problems/0142.环形链表II.md
@@ -186,6 +186,29 @@ public:
 
 
 Java：
+```java
+public class Solution {
+    public ListNode detectCycle(ListNode head) {
+        ListNode slow = head;
+        ListNode fast = head;
+        while (fast != null && fast.next != null) {
+            slow = slow.next;
+            fast = fast.next.next;
+            if (slow == fast) {// 有环
+                ListNode index1 = fast;
+                ListNode index2 = head;
+                // 两个指针，从头结点和相遇结点，各走一步，直到相遇，相遇点即为环入口
+                while (index1 != index2) {
+                    index1 = index1.next;
+                    index2 = index2.next;
+                }
+                return index1;
+            }
+        }
+        return null;
+    }
+}
+```
 
 
 Python：