leetcode

leetcode/141.py

@@ -0,0 +1,15 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution:
+    def hasCycle(self, head: Optional[ListNode]) -> bool:
+        h2=head
+        while h2 and h2.next:
+            head=head.next
+            h2=h2.next.next
+            if head==h2:
+                return True
+        return False