Update 0142.环形链表II.md

problems/0142.环形链表II.md

@@ -234,6 +234,29 @@ class Solution:
 ```
 
 Go：
+```func detectCycle(head *ListNode) *ListNode {
+    if head ==nil{
+        return head 
+    }
+    slow:=head
+    fast:=head.Next
+
+    for fast!=nil&&fast.Next!=nil{
+        if fast==slow{
+            slow=head
+            fast=fast.Next
+            for fast!=slow {
+                fast=fast.Next
+                slow=slow.Next
+            }
+            return slow
+        }
+        fast=fast.Next.Next
+        slow=slow.Next
+    }
+    return nil
+}
+```
 
 
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