A04 Solutions

Reference answers with reasoning. Try the ../exercises/ yourself first - the learning is in the struggle, not the answer key.

This directory has its own Makefile:

make all GPU_ARCH=gfx950      # build every solution for your GPU
make run                      # build + run all; every one must PASS
make clean

#	File	Notes
1	01_max_reduce_solution.cpp	fmaxf + -INFINITY identity; why -FLT_MAX is sometimes the better choice, and how NaN behaves.
2	02_fix_sync_solution.cpp	Both barriers restored, with the memory-model argument for each and the rule for where a barrier may not go.
3	03_reduction_analysis_solution.md	Full roofline arithmetic: 203 µs floor, 84% of achievable, where the remaining 16% goes, and the atomics code-review call.