1582 articles
Design a phone directory that manages available and allocated numbers with O(1) get, check, and release. Uses a queue of free numbers and a boolean availability array—the same pattern used in IP address allocation and database connection pools.
Design an in-memory key-value database with field-level get, set, delete, and sorted scan operations. Uses nested hashmaps and sorted structures—the foundation of Redis hashes and LeetCode contest scoring.
Implement a stack that retrieves the minimum element in O(1) using a parallel auxiliary stack. A foundational design pattern asked at Amazon, Google, and Meta—and used in undo systems and expression evaluators.
Maintain a running median from a data stream using two heaps: a max-heap for the lower half and a min-heap for the upper half. A classic FAANG hard problem used in analytics engines and streaming data pipelines.
Implement a circular queue (ring buffer) with O(1) enqueue, dequeue, and peek using head/tail pointer arithmetic. Used in embedded systems, producer-consumer pipelines, and network packet buffers at Amazon and Qualcomm.