Merged PyTorch Prep

What this is: a curated 24-problem "greatest hits" set, hand-picked from the larger Cartesia-specific and top-AI-labs practice sets for depth and pattern coverage, skewed away from anything trivial. Each page notes which original set and problem number it was curated from.

How to use this set

Work through in order; the numbering is a rough easier-pattern-to-harder progression grouped by category. Each problem page has a stub (src/<id>_<name>.py) to attempt first and a fully worked reference solution (src/<id>_<name>_solution.py) with step-by-step reasoning below it.