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Circular / Bounded Queue

A fixed-capacity FIFO over a ring buffer. Memory never grows — old data is either rejected or overwritten by policy.

What to know

  • Backpressure: a full queue signals producers to slow down.
  • Single-producer single-consumer rings can be lock-free.
  • Choice on overflow: block, drop-new, or overwrite-oldest.

In the wild: Kernel network buffers, audio pipelines, IoT telemetry buffers, Disruptor pattern in trading.

Algorithms to reach for

Ring-buffer enqueue/dequeue

O(1)

Constant-memory O(1) queue ops

Producer-consumer coordination

O(1) per item

Decouple fast producers from slow consumers

Practice problems — with full guides

Each problem has its own page: progressive hints, how to approach it, and the full solution.