> For the complete documentation index, see [llms.txt](https://sudoku.kazusa.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sudoku.kazusa.tech/full-marking-techniques/06-unique-loop.md).

# 唯一环（UL）

下面我们来看两种基于唯一矩形形式，从数字和结构两种方面拓展的新技巧。先看第一种。