{ } LinearCore interactive
Queue
First-In-First-Out. Enqueue, dequeue.
queue
size 3
← front (dequeue)back (enqueue) →
3
8
15
FIFO — elements leave in the exact order they arrived.
How it works
A queue is FIFO: elements leave in the order they arrived, like a line at a checkout. Implemented with a ring buffer or linked list, both ends are O(1). It powers schedulers, BFS, and every producer/consumer pipeline.
Mental models
- Two pointers — head and tail — move forward; the middle never shifts.
- A circular buffer reuses freed slots so memory stays bounded.
Complexity
- Enqueue
- O(1)
- Dequeue
- O(1)
- Peek
- O(1)
- Search
- O(n)
- Space
- O(n)
Reach for it when
- BFS traversal
- Task & job scheduling
- Streaming / buffering