kerrmudgeon

Were you able to complete the problem within reasonable time, otherwise?

As an interviewer, I get frustrated if the candidate wastes time writing excessively prolix text while missing the meat of the question. This is by no means an excuse for hostile conduct, and the additional context here makes it clear the interviewer is kind of a jerk in addition to being narrow-minded.

CUTLASS is a collection of CUDA C++ template abstractions for implementing high-performance matrix-multiplication (GEMM) at all levels and scales within CUDA. It incorporates strategies for hierarchical decomposition and data movement similar to those used to implement cuBLAS. CUTLASS decomposes these "moving parts" into reusable, modular software components abstracted by C++ template classes. These thread-wide, warp-wide, block-wide, and device-wide primitives can be specialized and tuned via custom tiling sizes, data types, and other algorithmic policy. The resulting flexibility simplifies their use as building blocks within custom kernels and applications.

I just wanted to clarify: private sales are person-to-person and cannot include any sort of shipment.

Online sales such as all the sites you listed are required by Federal law to only ship to a licensed Federal Firearms License holder who in turn may only transfer to customers after a NICS check. So, online sales are as cumbersome as in-store purchases.

Anything with a NICS check or credit card purchase is potentially trackable.

Also, with a gun registry [proposed in various places], sufficiently smart data mining, and fast processing, it may be possible to detect an ammunition purchase [via credit card] in a caliber in which the buyer supposedly doesn't have a registered firearm.