Yajilin
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Yajilin, sometimes called Arrow Ring, is a path-drawing and grid-shading logic puzzle where solvers must fill in cells based on numerical clues and then draw a continuous loop through the resulting grid.
Background
The name 'Yajilin' is a portmanteau of the Japanese word 'yajirushi', which means 'directing arrow' and the start of the word 'link'.
Yajilin as a genre was first published in June of 1999, in issue 86 of Puzzle Communication Nikoli and was invented by 天歩 ("Tenpo"). The genre was inspired by Yajisan-Kazusan, which appeared about a year earlier.[1]
Puzzle Application
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Yajilin puzzles are divided into two steps, although those steps may overlap in order to make certain logical deductions.
First, solvers must use the numbered arrows to place shaded 'obstacle' squares. As a rule, the arrows indicate exactly the number of shaded cells are between it and the edge of the puzzle (in the given direction), and those shaded cells cannot touch each other orthogonally.
The other step is creating a continuous loop that goes through every unshaded/non-clue cell in the puzzle. While not necessarily a heavily-constrained task, this must be possible after shading in all of the correct cells, and as a result care must be taken when doing the previous task to not create a grid where this is impossible.
TO DO
Strategy
TO DO
Examples
- The Neverending Story (MITMH 2022) (web) - This puzzle consists of 8 sub-puzzles spanning 4 different version of Yajilin: normal, One Off (where clues are one off the real number), Full Lane (where arrows indicate entire columns or rows rather than a direction), and Clued Loop (where the arrow clues count the number of line segments in that direction rather than shaded squares).
