English

Yin-Yang Puzzles are NP-complete

Computational Complexity 2021-06-30 v1 Computational Geometry

Abstract

We prove NP-completeness of Yin-Yang / Shiromaru-Kuromaru pencil-and-paper puzzles. Viewed as a graph partitioning problem, we prove NP-completeness of partitioning a rectangular grid graph into two induced trees (normal Yin-Yang), or into two induced connected subgraphs (Yin-Yang without 2×22 \times 2 rule), subject to some vertices being pre-assigned to a specific tree/subgraph.

Cite

@article{arxiv.2106.15585,
  title  = {Yin-Yang Puzzles are NP-complete},
  author = {Erik D. Demaine and Jayson Lynch and Mikhail Rudoy and Yushi Uno},
  journal= {arXiv preprint arXiv:2106.15585},
  year   = {2021}
}

Comments

10 pages, 11 figures. Proceedings of CCCG 2021

R2 v1 2026-06-24T03:43:50.486Z