DSA · Theory

XOR Linked List - A Memory Efficient Doubly Linked List

Theory

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XOR Linked List - A Memory Efficient Doubly Linked List

Ananya only reaches for XOR Linked List - A Memory Efficient Doubly Linked List when a ticket queue node has to stay correct in a counter.

XOR Linked List - A Memory Efficient Doubly Linked List on the board: head → next → …. Then say what a ticket queue node looks like after.

Without XOR Linked List - A Memory Efficient Doubly Linked List, a counter gets messy and a ticket queue node is hard to trust.

Use XOR Linked List - A Memory Efficient Doubly Linked List when a ticket queue node must stay clear. If a simpler DSA step works, use that instead.

Don’t do this with XOR Linked List - A Memory Efficient Doubly Linked List: losing the next pointer on delete. Interviewers spot it in ten seconds.

Place XOR Linked List - A Memory Efficient Doubly Linked List next to nearby DSA work — head → next → … is the link.

Viva for XOR Linked List - A Memory Efficient Doubly Linked List: what it is → head → next → … → the mistake (losing the next pointer on delete).

Diagram

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

Exam tip

Say XOR Linked List - A Memory Efficient 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

XOR Linked List - A Memory Efficient Doubly Linked List — a linked list chains nodes with next pointers instead of contiguous indexes.

Short notes

DefXOR Linked List - A Memory Efficient Doubly Linked List — Ananya uses it for a ticket queue node in a counter.
RuleXOR Linked List - A Memory Efficient Doubly Linked List → head → next → ….
RememberXOR Linked List - A Memory Efficient Doubly Linked List + time vs memory (a counter).
UseXOR Linked List - A Memory Efficient Doubly Linked List in a counter (a ticket queue node).
TrapXOR Linked List - A Memory Efficient Doubly Linked List — losing the next pointer on delete.
ExXOR Linked List - A Memory Efficient 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

XOR Linked List - A Memory Efficient Doubly Linked List

Example

Short notes

Questions

XOR Linked List - A Memory Efficient Doubly Linked List

Example

Short notes

Questions