Author: 红葉 (MOMIJI), from China, this question comes from his personal blog.
1.Divide the grid into L shaped blocks - one block wide. All blocks must be L shaped. 2.Cells with open circles form the knee (bend) in a block. 3.The number in an open circle shows the number of cells in its block.Open circles without numbers may have any number of cells. 4.Cells with arrows form one end of its block, the arrow points towards the knee of this block. 5.The number of marks in a block (arrows or open circles) may be 0, 1, 2, or 3.
Sashigane's puzzle was originally published in the 134th issue of "Puzzle Communication Nikoli" (March 2011), and it was published as a "half-fixed" puzzle in the 138th issue (March 2012). However, it was not upgraded to a "fixed fan" puzzle in the end, and the 149th issue issued in December 2014 became the last issue of nikoli to publish this puzzle.
See
Nikoli linkfor an example.
Solution code: From top to bottom, the number of different "L"s in each row.
on 3. September 2021, 01:35 by cdwg2000
Slightly modify solution code description, thank you SudokuExplorer.