DSA · Theory

Priority Queue using Linked list

Theory

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Don’t start Priority Queue using Linked list with jargon. Start with a ticket queue node. That is the whole point.

For Priority Queue using Linked list, Big-O is in play. Don’t blame it until you have traced a ticket queue node.

Skip Priority Queue using Linked list and losing the next pointer on delete shows up in a counter.

Rohit ships Priority Queue using Linked list in a counter. That is the use case worth saying.

Priority Queue using Linked list miss — losing the next pointer on delete. Fix it before you talk about advanced DSA.

Place Priority Queue using Linked list next to nearby DSA work — head → next → … is the link.

Close Priority Queue using Linked list with: “If I skip it, a ticket queue node goes wrong like this: losing the next pointer on delete.”

Diagram

  front → [A][B][C] ← rear
  out ↑         ↑ in
       FIFO

Exam tip

For Priority Queue using Linked list: definition + a counter + one failure.

from collections import deque

q = deque()
q.append(10)      # enqueue
q.append(20)
print(q.popleft())  # 10
print(list(q))

Priority Queue using Linked list — queue is FIFO. deque.popleft() is O(1).

DefPriority Queue using Linked list — Rohit uses it for a ticket queue node in a counter.
RulePriority Queue using Linked list → head → next → ….
RememberPriority Queue using Linked list + Big-O (a counter).
UsePriority Queue using Linked list in a counter (a ticket queue node).
TrapPriority Queue using Linked list — losing the next pointer on delete.
ExPriority Queue using Linked list → a ticket queue node.