Idea: Exploring the PP Algorithm for Derangements

[Yusheng-Hu]

I'm considering whether the PP Algorithm's bitmask-backtracking could be a useful alternative to CAT algorithms for derangements.

Bitwise Logic: It may offer high efficiency for constraint checking via bitwise operations.

Multiset Support: The mask logic could potentially be adapted for multisets (e.g., {1,1,2,2,3}) by filtering value-types.

Parallel Potential: Its recursive structure might allow for simpler multi-core parallelization compared to serial generators.

I'd love to hear the community's thoughts on whether this direction is worth exploring for practical counting or constrained search tasks.