Reverse the first K elements of a Queue.

Updated Apr 28, 2026

Short answer

Use an auxiliary stack to flip the first K elements, then rotate the rest.

Deep explanation

Mid-level queue concepts involve specific optimizations and algorithm integration. Use an auxiliary stack to flip the first K elements, then rotate the rest.

Real-world example

Managing requests in a web server buffer.

Common mistakes

  • Forgetting to reset pointers to -1 when the last element is dequeued.

Follow-up questions

  • What is the time complexity of Heap-based PQ push?

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