From 6a68c343f5eb296edb4ad092fdb5ad62d85985a8 Mon Sep 17 00:00:00 2001
From: ganavi <ganavi.h321.com>
Date: Sun, 1 Nov 2026 16:43:50 +0530
Subject: [PATCH 1/2] Optimize Node.has_loop to use constant auxiliary space
 (Fixes #15576)

---
 data_structures/linked_list/has_loop.py | 74 +++++--------------------
 1 file changed, 15 insertions(+), 59 deletions(-)

diff --git a/data_structures/linked_list/has_loop.py b/data_structures/linked_list/has_loop.py
index a25204e3c4ce..54e127c9afdc 100644
--- a/data_structures/linked_list/has_loop.py
+++ b/data_structures/linked_list/has_loop.py
@@ -1,63 +1,19 @@
-from __future__ import annotations
-
-from collections.abc import Iterator
-from typing import Any
-
-
-class ContainsLoopError(Exception):
-    pass
-
-
-class Node:
-    def __init__(self, data: Any) -> None:
-        self.data: Any = data
-        self.next_node: Node | None = None
-
-    def __iter__(self) -> Iterator[Any]:
-        node = self
-        visited = set()
-        while node:
-            if node in visited:
-                raise ContainsLoopError
-            visited.add(node)
-            yield node.data
-            node = node.next_node
-
-    @property
-    def has_loop(self) -> bool:
-        """
-        A loop is when the exact same Node appears more than once in a linked list.
-        >>> root_node = Node(1)
-        >>> root_node.next_node = Node(2)
-        >>> root_node.next_node.next_node = Node(3)
-        >>> root_node.next_node.next_node.next_node = Node(4)
-        >>> root_node.has_loop
-        False
-        >>> root_node.next_node.next_node.next_node = root_node.next_node
-        >>> root_node.has_loop
-        True
+@property
+def has_loop(self) -> bool:
         """
-        try:
-            list(self)
-            return False
-        except ContainsLoopError:
-            return True
+        Detect whether the linked list contains a cycle using Floyd's
+        Cycle-Finding Algorithm (Tortoise and Hare).
 
+        Time Complexity: O(n)
+        Auxiliary Space: O(1)
+        """
+        slow = self
+        fast = self.next
 
-if __name__ == "__main__":
-    root_node = Node(1)
-    root_node.next_node = Node(2)
-    root_node.next_node.next_node = Node(3)
-    root_node.next_node.next_node.next_node = Node(4)
-    print(root_node.has_loop)  # False
-    root_node.next_node.next_node.next_node = root_node.next_node
-    print(root_node.has_loop)  # True
-
-    root_node = Node(5)
-    root_node.next_node = Node(6)
-    root_node.next_node.next_node = Node(5)
-    root_node.next_node.next_node.next_node = Node(6)
-    print(root_node.has_loop)  # False
+        while fast is not None and fast.next is not None:
+            if slow is fast:
+                return True
+            slow = slow.next
+            fast = fast.next.next
 
-    root_node = Node(1)
-    print(root_node.has_loop)  # False
+        return False
\ No newline at end of file

From 1fd7a6ea043d7c1d6382f84e8f2cde41d51eaca9 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sun, 1 Nov 2026 11:37:04 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 data_structures/linked_list/has_loop.py | 28 ++++++++++++-------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/data_structures/linked_list/has_loop.py b/data_structures/linked_list/has_loop.py
index 54e127c9afdc..e5e72c4f628d 100644
--- a/data_structures/linked_list/has_loop.py
+++ b/data_structures/linked_list/has_loop.py
@@ -1,19 +1,19 @@
 @property
 def has_loop(self) -> bool:
-        """
-        Detect whether the linked list contains a cycle using Floyd's
-        Cycle-Finding Algorithm (Tortoise and Hare).
+    """
+    Detect whether the linked list contains a cycle using Floyd's
+    Cycle-Finding Algorithm (Tortoise and Hare).
 
-        Time Complexity: O(n)
-        Auxiliary Space: O(1)
-        """
-        slow = self
-        fast = self.next
+    Time Complexity: O(n)
+    Auxiliary Space: O(1)
+    """
+    slow = self
+    fast = self.next
 
-        while fast is not None and fast.next is not None:
-            if slow is fast:
-                return True
-            slow = slow.next
-            fast = fast.next.next
+    while fast is not None and fast.next is not None:
+        if slow is fast:
+            return True
+        slow = slow.next
+        fast = fast.next.next
 
-        return False
\ No newline at end of file
+    return False