Queue
Domain: Data Structures
🎯 Motivation
When you need first-in-first-out behaviour — printer jobs, customer service lines, task scheduling — a queue is the right structure.
📋 Concrete Example
Python: from collections import deque; q = deque(); q.append('a'); q.append('b'); q.popleft() returns a (first added).
🔗 Analogy
A queue at a bubble tea shop. The first person to line up is the first to get their drink. New people join at the back.