Definition
Queue is a FIFO (First In First Out) data structure. The first item added is the first to be removed, just like waiting in line.
Key Characteristics
- ✓FIFO (First In, First Out) structure - First item in is first out
- ✓Enqueue and Dequeue operations in O(1) time
- ✓Managed with two pointers: Front and Rear
- ✓Used in BFS (Breadth-First Search), task scheduling, etc.
Use Cases
Used in these scenarios:
Bank Queue
Customers who arrive first are served first. This is the most common real-life example of a queue.
Print Queue
When multiple people use a printer, print jobs are processed in the order they were requested.
BFS Traversal
Queue is used for breadth-first traversal of graphs or trees. Visits nearby vertices first.
Task Scheduler
Operating systems and programs use queues to process tasks in order.
Operations
Main operations:
enqueue
O(1)Add a new element to the rear of the queue.
dequeue
O(1)Remove and return the element at the front of the queue.
front / peek
O(1)View the front element without removing it.
isEmpty
O(1)Check if the queue is empty.
Complexity
Time Complexity
Space Complexity
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