update readme

Author: hogan-tech

0142-linked-list-cycle-ii/0142-linked-list-cycle-ii.py

@@ -1,5 +1,13 @@
+# time complexity: O(n)
+# space complexity: O(n)
+from typing import Optional
 
 
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
 
 class Solution:
     def detectCycle(self, head: Optional[ListNode]) -> Optional[ListNode]:
@@ -12,6 +20,30 @@ def detectCycle(self, head: Optional[ListNode]) -> Optional[ListNode]:
             node = node.next
         return None
 
+# time complexity: O(n)
+# space complexity: O(1)
+class Solution:
+    def detectCycle(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        slow = head
+        fast = head
+
+        while fast and fast.next:
+            slow = slow.next
+            fast = fast.next.next
+
+            if slow == fast:
+                break
+
+        if not fast or not fast.next:
+            return None
+
+        fast = head
+
+        while slow != fast:
+            slow = slow.next
+            fast = fast.next
+
+        return slow
 
 head = ListNode(3)
 head.next = ListNode(2)

3616-make-array-elements-equal-to-zero/3616-make-array-elements-equal-to-zero.py

@@ -115,31 +115,3 @@ It helps others discover the repo and keeps the project growing.
 ---
 
 Feedback / Questions → open an Issue or reach out on [LinkedIn](https://www.linkedin.com/in/hogan-l/)  
-
-<!---LeetCode Topics Start-->
-# LeetCode Topics
-## Array
-|  |
-| ------- |
-| [3616-make-array-elements-equal-to-zero](https://github.com/hogan-tech/leetcode-solution/tree/master/3616-make-array-elements-equal-to-zero) |
-## Simulation
-|  |
-| ------- |
-| [3616-make-array-elements-equal-to-zero](https://github.com/hogan-tech/leetcode-solution/tree/master/3616-make-array-elements-equal-to-zero) |
-## Prefix Sum
-|  |
-| ------- |
-| [3616-make-array-elements-equal-to-zero](https://github.com/hogan-tech/leetcode-solution/tree/master/3616-make-array-elements-equal-to-zero) |
-## Hash Table
-|  |
-| ------- |
-| [0142-linked-list-cycle-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0142-linked-list-cycle-ii) |
-## Linked List
-|  |
-| ------- |
-| [0142-linked-list-cycle-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0142-linked-list-cycle-ii) |
-## Two Pointers
-|  |
-| ------- |
-| [0142-linked-list-cycle-ii](https://github.com/hogan-tech/leetcode-solution/tree/master/0142-linked-list-cycle-ii) |
-<!---LeetCode Topics End-->