DSA — Circular Linked Lists

What is a Circular Linked List?

A linked list where the last node points back to the first node.

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class CircularLinkedList:
    def __init__(self):
        self.head = None

Insert at End

def insert(self, data):
    new_node = Node(data)
    if not self.head:
        self.head = new_node
        new_node.next = self.head
        return
    current = self.head
    while current.next != self.head:
        current = current.next
    current.next = new_node
    new_node.next = self.head

Delete by Value

def delete(self, data):
    if not self.head:
        return
    
    if self.head.data == data:
        if self.head.next == self.head:
            self.head = None
        else:
            current = self.head
            while current.next != self.head:
                current = current.next
            current.next = self.head.next
            self.head = self.head.next
        return
    
    current = self.head
    while current.next != self.head:
        if current.next.data == data:
            current.next = current.next.next
            return
        current = current.next

Display

def display(self):
    if not self.head:
        return
    current = self.head
    while True:
        print(current.data, end=" -> ")
        current = current.next
        if current == self.head:
            break
    print("(back to head)")

Mini Practice

1. Implement a circular linked list
2. Insert and delete nodes
3. Traverse the circular list
4. Detect if a list is circular

Up Next

Continue with Stacks — stack data structure.