From 4a8fc274940cc03b6d7b15fe2a18b533f9ab3550 Mon Sep 17 00:00:00 2001
From: santhoshtk <santhoshofficial.py@gmail.com>
Date: Fri, 2 Dec 2022 20:40:54 +0530
Subject: [PATCH] Add circular linked list

---
 .../Python/linked_lists/circularLinkedList.py | 130 ++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 algorithms/Python/linked_lists/circularLinkedList.py

diff --git a/algorithms/Python/linked_lists/circularLinkedList.py b/algorithms/Python/linked_lists/circularLinkedList.py
new file mode 100644
index 00000000..de56a315
--- /dev/null
+++ b/algorithms/Python/linked_lists/circularLinkedList.py
@@ -0,0 +1,130 @@
+"""
+Data Structure : Circular Linked List.
+Time Complexity : O(1) for all operations.
+Space Complexity : O(n) Where, 'n' is the number of nodes in the linked list.
+"""
+
+
+class Node:
+    """
+    Class to represent a Node.
+    Attributes:
+        - value (int) : The value of the node.
+        - next (Node) : The reference of the next node.
+    """
+
+    def __init__(self, value: int):
+        self.value = value
+        self.next = None
+
+
+class CircularLinkedList:
+    """
+    CLass to represent circular linked list and perform its operations.
+    Attributes:
+        - head (Node) : The first node in the linked list.
+        - tail (Node) : The last node in the linked list.
+    """
+
+    def __init__(self):
+        self.head = None
+        self.tail = None
+
+    def __iter__(self):
+        trackNode = self.head
+        while trackNode.next != self.head:
+            yield trackNode.value
+            trackNode = trackNode.next
+        yield trackNode.value
+
+    def __str__(self):
+        result = ""
+        for value in self:
+            result += f'{value} -> '
+
+        return result
+
+    def isEmpty(self) -> bool:
+        """Return 'True' if the circular linked list is Empty. Otherwise, return 'False'."""
+        if self.head is None:
+            return True
+        else:
+            return False
+
+    def insertNode(self, value: int, location: int = -1) -> None:
+        """
+        Insert the node at the given location. Default in the end.
+        Args:
+            - value (int): The value of the node.
+            - location (int): The position of the node to insert into the linked list.
+                - 0 : At the beginning.
+                - -1 : At the end.
+                - Any `int` : At the specified location.
+        """
+
+        newNode = Node(value)
+
+        # Insertion at the beginning of the circular linked list.
+        if location == 0:
+            if not self.isEmpty():
+                self.head = newNode
+                newNode.next = self.tail.next
+                self.tail.next = self.head
+            else:
+                self.head = self.tail = newNode
+                newNode.next = newNode
+
+        # Insertion at the end of the circular linked list.
+        elif location == -1:
+            if not self.isEmpty():
+                newNode.next = self.tail.next
+                self.tail.next = newNode
+                self.tail = newNode
+            else:
+                self.head = self.tail = newNode
+                newNode.next = newNode
+        else:
+            trackLocation = 0
+            trackNode = self.head
+
+            while trackLocation < trackLocation - 1:
+                trackNode = trackNode.next
+                trackLocation += 1
+
+            nextNode = trackNode.next
+            trackNode.next = newNode
+            newNode.next = nextNode
+
+    def deleteNode(self, value: int) -> None:
+        """
+        Delete the node if the value exist in the linked list.
+        Args:
+            - value (int) : The value of the node.
+        """
+        if not self.isEmpty():
+            trackNode = self.head
+            previousNode = None
+            while trackNode.value != value:
+                previousNode = trackNode
+                trackNode = trackNode.next
+
+            if trackNode == self.head:
+                self.head = self.head.next
+                self.tail.next = self.head
+            elif trackNode == self.tail:
+                previousNode.next = self.head
+            else:
+                previousNode.next = trackNode.next
+        else:
+            print("The linked list is Empty.")
+
+
+# TESTING THE CIRCULAR LINKED LIST
+cll = CircularLinkedList()
+cll.insertNode(10)
+cll.insertNode(20)
+cll.insertNode(1000, 1)
+cll.insertNode(20)
+
+cll.deleteNode(1000)
+print(cll)