DSA · Theory

Queue for Competitive Programming

Theory

584/810

Queue for Competitive Programming

Queue for Competitive Programming is a DSA topic. In plain words you use it for print jobs in a lab printer. Don’t start with a slogan — start with that picture.

Smallest example: enqueue / dequeue FIFO. Type it, run it, and say what you see. If you can do that from memory, you know Queue for Competitive Programming.

From the example next to this theory — Queue for Competitive Programming — queue is FIFO.

Trap — confusing front and rear. Fix that before you talk about advanced DSA.

Viva — what is Queue for Competitive Programming? Then show enqueue / dequeue FIFO. Then name the trap.

Diagram

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

Exam tip

What is Queue for Competitive Programming? Show this: enqueue / dequeue FIFO. Trap: confusing front and rear.

Example

from collections import deque

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

Queue for Competitive Programming — queue is FIFO. deque.popleft() is O(1).

Short notes

DefQueue for Competitive Programming — print jobs in a lab printer.
Ruleenqueue / dequeue FIFO
Trapconfusing front and rear
Usea lab printer

DSA · Theory

Queue for Competitive Programming

← All stacks

Theory

584/810

Queue for Competitive Programming

Queue for Competitive Programming is a DSA topic. In plain words you use it for print jobs in a lab printer. Don’t start with a slogan — start with that picture.

Smallest example: enqueue / dequeue FIFO. Type it, run it, and say what you see. If you can do that from memory, you know Queue for Competitive Programming.

From the example next to this theory — Queue for Competitive Programming — queue is FIFO.

Trap — confusing front and rear. Fix that before you talk about advanced DSA.

Viva — what is Queue for Competitive Programming? Then show enqueue / dequeue FIFO. Then name the trap.

Diagram

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

Exam tip

What is Queue for Competitive Programming? Show this: enqueue / dequeue FIFO. Trap: confusing front and rear.

Example

from collections import deque

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

Queue for Competitive Programming — queue is FIFO. deque.popleft() is O(1).

Short notes

DefQueue for Competitive Programming — print jobs in a lab printer.
Ruleenqueue / dequeue FIFO
Trapconfusing front and rear
Usea lab printer

Queue for Competitive Programming

Example

Short notes

Questions

Queue for Competitive Programming

Example

Short notes

Questions