Overview

This section covers interview problems that leverage stack and queue data structures, FIFO processing, and order book design.

Problem	Level	Key Concepts
Calculate PnL from Stock Transactions	L3-L4	FIFO lot tracking, hash map of queues, partial consumption
Building a Market Order Book	L3-L5	Sorted structures, heaps, bucket arrays, bounded-price optimization
Processing Highway Toll Logs	L3-L5	Batch processing, log pairing, prefix sums, MapReduce at scale
Find the Shortest Queue	L3-L4	Round-robin interleaving, minimizing expensive operations