Logic Masters Deutschland e.V.

Initial Setter Difficulty: 3/5

Normal Sudoku rules apply.
Place the digits 1-9 so that they do not repeat in any row, column, or 3x3 box.

Dutch Flats
Every 5 in the grid must have a 1 directly above it or a 9 directly below it. It may have both, but it doesn't need both.

Japanese Sums
The clues outside the grid indicate the order of the runs of contiguous cells that must be shaded the color of the clue. The number in the clue indicates the value of the sum of the cells in the run.
? represents a single digit sum total.
?? represents a double digit sum total.
All cells are shaded and all shading clues are given.

Special Thanks - Incredibly this is Dutch Flat Mate Number 52!
This started out as a silly little idea that I expected to fizzle out, and suddenly we're at the point where there has been one every Wednesday for a whole year.
Massive thank you to the setters who have offered their services in setting Dutch Flat Mates: Palpot, Marty_Sears, Sujoyku, gdc, Damo_89 and SamuPiano* (*upcoming in the next few weeks) as well as a few others who have attempted to make drafts, but most of all thank you to Goodcity.

This series wouldn't exist how it does without Goodcity. I would have paused the run last Christmas but he wanted to keep it going.
This in turn inspired me to also want to keep it going. At times it felt like we were scrambling for ideas for future drafts, and even half a year didn't feel possible.
Goodcity has also been the primary tester for my drafts, with Palpot also deserving gratitude for testing a lot of them for me.

Thank you to the setters who have used the constraint in puzzles that weren't part of the Wednesday series, including antiknight, gdc, Lake and Gnubeutel.

Massive thanks to the content creators who have live solved these puzzles, sometimes being prepared to live solve an untested draft or two. Biggest shout out to OlliWright who has live solved every one.

And a huge thank you to the solvers, because without you this would be a lot of effort for nothing - haha. I see a lot of regular names on the DFM solve lists.

This isn't the end, we still have plenty of puzzles in a finished state waiting for their turn.

To play this weeks puzzle, Dutch Flat Mates (Japanese Sums), please click here: Play CTC

Hint to Start

The easy stuff is colouring the perimeter and working inwards from the ?? clues. After that I would recommend focusing on shading C8 and C9 and flat mates on that side of the grid, but you'll then need to move across the grid for more progress.

Hint to End

Probably stuff like "can I put a 9 in a two cell '?' clue?" and "I haven't used that >15 in Row 1 yet, I wonder if it's important" - haha - you got this :)

Example Puzzle
This puzzle is intended to provide an example for the Japanese Sums constraint (it only logically solves as a toroidal Dutch Flat Mate).

This Weeks Puzzle

Previous puzzles in the Dutch Flat Mates series:

• #01 - 18 Oct 23 - Classic
• #02 - 25 Oct 23 - Thermometers
• #03 - 01 Nov 23 - German Whispers
• #04 - 08 Nov 23 - Region Sum Lines
• #05 - 15 Nov 23 - Sandwich Sums
• #06 - 22 Nov 23 - Little Killer
• #07 - 29 Nov 23 - Kropki
• #08 - 05 Dec 23 - Zipper Lines
• #09 - 12 Dec 23 - Renban - By GoodCity
• #10 - 19 Dec 23 - Nabner - By GoodCity
• #11 - 26 Dec 23 - Skyscrapers - By GoodCity
• #12 - 03 Jan 24 - Dutch Whispers
• #13 - 10 Jan 24 - Killer Cages
• #14 - 17 Jan 24 - Arrows
• #15 - 24 Jan 24 - Ten Lines
• #16 - 31 Jan 24 - 159 Index and Even - By GoodCity
• #17 - 07 Feb 24 - Friendly Cells
• #18 - 14 Feb 24 - Quads
• #19 - 21 Feb 24 - Silent Killer - By GoodCity
• #20 - 28 Feb 24 - XV and Equality
• #21 - 06 Mar 24 - X-Sums
• #22 - 13 Mar 24 - Numbered Rooms - By GoodCity
• #23 - 20 Mar 24 - Diagonal X-Sums
• #24 - 27 Mar 24 - Yin Yang (Neighborhoods) - By Palpot
• #25 - 03 Apr 24 - Hit Points
• #26 - 10 Apr 24 - Counting Circles
• #27 - 17 Apr 24 - XY Difference - By GoodCity
• #28 - 24 Apr 24 - Double Sandwich Sums
• #29 - 01 May 24 - Foggy Knights
• #30 - 08 May 24 - Look and Say Little Killer
• #31 - 15 May 24 - Slingshot - By GoodCity
• #32 - 22 May 24 - 258 Index and Odd
• #33 - 29 May 24 - Rellik
• #34 - 05 Jun 24 - Search 9 - By Palpot
• #35 - 12 Jun 24 - Diagonal Outside
• #36 - 19 Jun 24 - Entropic Snake - Collab with Palpot
• #37 - 26 Jun 24 - Rossini - By GoodCity
• #38 - 03 Jul 24 - Pointer Arrows
• #39 - 10 Jul 24 - Same Difference - by Marty Sears
• #40 - 17 Jul 24 - Battenburg and Average Arrows
• #41 - 24 Jul 24 - Omnipotent Lines - by Sujoyku
• #42 - 31 Jul 24 - Modular Snake
• #43 - 7 Aug 24 - Hot and Cold Lines - by Marty Sears
• #44 - 14 Aug 24 - Minmax Quads - by Sujoyku
• #45 - 21 Aug 24 - Quad Sums - By GoodCity
• #46 - 28 Aug 24 - Entropic Whispers - by gdc
• #47 - 4 Sep 24 - Thripper Lines
• #48 - 11 Sep 24 - Index Lines - by Marty Sears
• #49 - 18 Sep 24 - Kroopki Doots - by Damo_89
• #50 - 25 Sep 24 - Frameless / X-Less X-Sums
• #51 - 02 Oct 24 - Full Rank - By GoodCity