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Circular Linked List

Traversal​

def traversal(head):
    if not head:
        return
    print(head.val)
    curr = head.next
    while curr != head:
        print(curr.val)
        curr = curr.next

Insert at beginning​

# insert at 2nd position then swap
def insertAtBeginning(head, x):
    t = Node(x)
    if not head:
        t.next = t
        return t
    t.next = head.next
    head.next = t
    head.val, t.val = t.val, head.val
    return head

Insert at end​

# insert at 2nd position, swap, then return 2nd
def insertAtEnd(head, x):
    t = Node(x)
    if not head:
        t.next = t
        return t
    t.next = head.next
    head.next = t
    t.val, head.val = head.val, t.val
    return t

Delete first​

def delFirst(head):
    if head == None or head.next == head:
        return None
    head.val = head.next.val
    head.next = head.next.next
    return head