Tag Archives: japanese sums

Puzzle 154: The Largest Number

Posting from the evening after the 2018 German Logic Masters. It went decently well for me, with a third place after the main rounds which means I’m on the A-team again. My results on the two Rätselportal-rounds were bad as expected. On the other hand, finishing that fences sprint round first with quite a margin after 3:15 of 20:00 minutes was great. An unfortunate marking mistake in the final playoffs saw me lose a couple of minutes of time double-checking my correct solution. With no good way to fix this, I ended up fourth with the knowledge that first place was possible.

I made a couple of puzzles to prepare, two of which I’ve published on the Rätselportal already: A Japanese Sums/Masyu hybrid and a hand-constructed (with the help of a friend, thank you!) unclued 5×5 skyscraper blocks that I’m very happy with!

Some more I’ll post here. To start, here’s a The Largest Number. The type was introduced at the 2017 WPC in India. I don’t think I’ve seen one without given numbers before.

Rules Fill the grid with numbers such that each room contains the numbers from 1 to the size of the room. Equal numbers can not be next to each other horizontally or vertically. Circle the largest number in each room. Then also circled numbers can not be next to each other horizontally or vertically.

Puzzle 104: Keller, Japanese Sums+Dotted Snake

Last of the Kellers, and the hardest. You really can’t say I wasn’t prepared.


Rules The left grid is a Japanese Sums puzzle, digits 1-8. Place digits in some cells, so that they don’t repeat in rows or columns. Clues give the sums of blocks of adjacent digits in order. The right grid is a Dotted Snake: Draw a snake of any length that occupies full cells and doesn’t touch itself, not even diagonally. Numbering the snake cells from head to tail, put a dot in every third cell, starting with the third. Clues indicated the number of dotted snake cells in the corresponding row or column.

The grids interact: There must be a digit under every snake cell, and that digit must be divisible by three if and only if the corresponding snake cell is dotted.

Puzzle 94: JaTaHoKu

Another JaTaHoKu I just made, to prove to myself that it’s possible to make accessible JaTaHoKus. You might want to solve this one before the previous one.


Rules Place numbers from 1 to 5 into some empty cells, such that each row, column and region contains each number exactly once. Clues within the grid are Tapa clues; the numbered cells form a valid Tapa solution with respect to these. Clues along the bottom and right edges are skyscraper clues. Clues along the top and left are Japanese Sums clues, with question marks standing in for unspecified digits. (I.e., 10 would be two question marks.)

Puzzle 66: Japanese Sums with 0

Long time no post. I’ve been making puzzles for croco-puzzle recently, the ongoing Best of 24h series, in particular.

But, here’s a practice puzzle for the coming German GP round next weekend. It’s on the hard side — I’d be interested to hear if you find (a way around) the intended break-in.


Rules Shade some cells, and fill the remaining cells with digits from 0 to 6, such that no digit occurs more than once in each row or column. The numbers outside the grid indicate the sums of blocks of connected digits in the correct order. This includes single digits.

Example (digits 0-3)japanischesummennull-example

Puzzle 22: Japanese Sums and Loop

The Czech round of the puzzle GP will take place next week, the instruction booklet has been posted. Here’s a practice puzzle for one of the types.


Rules Place numbers from 1 to 6 in some cells so that no number repeats within a row or column. For rows and columns that have clues given on the outside, these numbers correspond to all sums of blocks of adjacent digits within that line, in the correct order. Furthermore, draw a loop that visits all cells without a number, passing horizontally and vertically from cell centre to cell centre.