or solve online (using our beta test of Penpa-Edit tools)
Theme: Logical
Answer String: Enter the length in cells of each of the shaded segments from left to right for the marked rows, starting at the top. Separate each row’s entry from the next with a comma.
Time Standards (highlight to view): Grandmaster = 1:20, Master = 2:30, Expert = 5:00
Solution: PDF
(View image directly for larger form.)
or solve online (using our beta test of Penpa-Edit tools)
Theme: Clue symmetry and logic
Rules: Standard Yajilin rules.
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 8:30, Master = 12:00, Expert = 24:00
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools)
Theme: Two by Three by Four
Answer String: Enter the 1st column from top to bottom, followed by a comma, followed by the 9th column from top to bottom.
Time Standards (highlight to view): Grandmaster = 3:15, Master = 4:30, Expert = 9:00
Solution: PDF
Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.
or solve online (using our beta test of Penpa-Edit tools)
Theme: Logical
Rules: Standard Yajilin rules.
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 2:30, Master = 3:30, Expert = 7:00
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools)
Theme: Paired Islands
Rules: Standard Nurikabe rules.
Answer String: Enter the length in cells of each of the black segments (the unnumbered, connected “ocean”) from left to right for the marked rows, starting at the top. Separate each row’s entry from the next with a comma.
Time Standards (highlight to view): Grandmaster = 1:00, Master = 1:20, Expert = 2:40
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools)
Theme: Almost All Two Easy!
Rules: Standard Yajilin rules.
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 0:55, Master = 1:10, Expert = 2:20
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s)
Theme: TC
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 1:00, Master = 1:30, Expert = 3:00
Editor’s Note: Today we add Tom Collyer to our list of Contributing Puzzlemasters. A noted sudoku solver and puzzle author, Tom’s Friday Puzzles have been an online puzzle mainstay for many years — not to be confused with Thomas‘s Friday Puzzle which started around the same time.
Solution: PDF
We will soon begin to regularly post Yajilin puzzles here. Yajilin is a style that is quite different from the other loop styles we have at the moment. Most of those have to do with how a loop travels in small regions. Masyu puzzles, for example, contain clues that require a loop to go straight or turn in specific cells; most of the logic focuses around how to make the loop obey these path instructions. Yajilin is focused more on where a loop travels, which is almost everywhere in the grid. As a variation on other “visit all cells” loop puzzles, the logic in Yajilin revolves around how to get in and out of every part of the grid with only a few cells untouched.
While the style may be familiar, our Yajilin will not look exactly like the Yajilin puzzles you are used to seeing elsewhere. We strongly believe that a wider range of puzzles, and more interesting puzzles, are possible if constructors are allowed to mark some cells as “unused” — neither white nor black. In the standard format, all of these spots would then need arrow clues resulting in excessive and often redundant clues that can subtract from the potential aesthetics or logic of a puzzle. It would simply be impossible to make a standard Yajilin with the curious but pedagogical properties of this example puzzle below.
Increasing the flexibility for the puzzle designer to include known spots that the loop cannot enter seems to meaningfully increase the range of possible Yajilin puzzles. So this is what Grandmaster Puzzles will do with our Yajilin puzzles (although sometimes they may still look “classic”). We hope the change only adds to your enjoyment of this puzzle style.
or solve online (using our beta test of Penpa-Edit tools)
Theme: Easy as (0,) 1, 2, 3?
Rules: Standard Yajilin rules.
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 1:15, Master = 2:30, Expert = 5:00
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools)
Theme: Rise and Fall
Rules: Standard Cross the Streams rules.
Answer String: Enter the length in cells of each of the black segments from top to bottom for the marked columns, going in order from A to B to C to D and separating each entry with a comma.
Time Standards (highlight to view): Grandmaster = 6:00, Master = 10:30, Expert = 21:00
Solution: PDF
or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s)
This is a “Franken-Friday” puzzle variation.
Theme: Half Truths
Rules: Variation of Masyu rules. Half of the circles are lying; a lying white circle is actually a black circle and a lying black circle is actually a white circle. The loop must alternate between true circles and lying circles (T-L-T-L-…).
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Time Standards (highlight to view): Grandmaster = 5:30, Master = 10:00, Expert = 20:00
Solution: PDF