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Circular Doubly Linked List

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Circular Doubly Linked List

Circular Doubly Linked List is simple if you keep it on paper. Priya uses it for a ticket queue node in a counter.

Circular Doubly Linked List on the board: head → next → …. Then say what a ticket queue node looks like after.

Circular Doubly Linked List exists so Priya can keep a ticket queue node correct in a counter.

Circular Doubly Linked List shows up in a counter. Name a ticket queue node, not “a real-world scenario”.

Circular Doubly Linked List miss — losing the next pointer on delete. Fix it before you talk about advanced DSA.

Place Circular Doubly Linked List next to nearby DSA work — head → next → … is the link.

Close Circular Doubly Linked List with: “If I skip it, a ticket queue node goes wrong like this: losing the next pointer on delete.”

Diagram

  [10] → [20] → [30] → /
   head              tail

Exam tip

Say Circular Doubly Linked List in one breath, then head → next → …, then losing the next pointer on delete.

Example

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

head = Node(1, Node(2, Node(3)))
cur = head
while cur:
    print(cur.val, end=" -> " if cur.next else "\n")
    cur = cur.next

Circular Doubly Linked List — a linked list chains nodes with next pointers instead of contiguous indexes.

Short notes

DefCircular Doubly Linked List — Priya uses it for a ticket queue node in a counter.
RuleCircular Doubly Linked List → head → next → ….
RememberCircular Doubly Linked List + a dry-run table (a counter).
UseCircular Doubly Linked List in a counter (a ticket queue node).
TrapCircular Doubly Linked List — losing the next pointer on delete.
ExCircular Doubly Linked List → a ticket queue node.

class Node: def __init__(self, val, next=None): self.val = val self.next = next head = Node(1, Node(2, Node(3))) cur = head while cur: print(cur.val, end=" -> " if cur.next else "\n") cur = cur.next

Circular Doubly Linked List

Example

Short notes

Questions

Circular Doubly Linked List

Example

Short notes

Questions