Tag Archives: medium

Puzzle 144: Easy as ABC (Zehnkampf)

Last weekend I took part in a puzzle decathlon, run by Berni of croco-puzzle. That involved 10 rounds modelled on the athletics decathlon, where the running events mapped to puzzle solving (the hurdles were possible broken puzzles), jumping events mapped to puzzle creation, and throwing events mapped to optimization puzzles. A lot of very original ideas, and overall it worked very well. Puzzles and results are available at logic-masters.de.

One of the construction rounds, the Pole Vault, gave you three tries at constructing a high-scoring Easy as ABC puzzle: Before each attempt, you chose a grid size, then had 15 minutes to extend a partially clued puzzle of that size to a correct puzzle. The score was calculated by subtracting twice the number of added outside clues, five times the number of inside clues and once the number of diagonal adjacencies in the solution from ten times the number of rows/columns. I had a rough start there, but ended up with a pretty good third try, with this 8 by 8 puzzle.


Rules Place letters A-C into the grid so that each letter occurs once in each row and column. Clues indicate the first letter in the corresponding row or column.

Puzzle 143: Nanro Signpost

Here’s a Nanro Signpost.


Rules Shade some cells, so that all shaded cells are connected, and such that shaded cells don’t fill any 2×2 square. Clues indicated the number of shaded cells in an area; each area must have at least one shaded cell. Whenever two shaded cells touch across walls, the number of shaded cells within both areas must be different.

Puzzle 141: Twin-Detector Sudoku (diagonal)

The WSC 2016 is over. I have a lot of puzzles left to solve, but I’m quite happy with my result (54th in the general ranking, after the 39th official participant, after 89/63 last year). Here’s a puzzle I made to help Martin to prepare to become the King of the Mountains (not sure that helped, considering I didn’t quite have the rules right). Test-solved by the new world champion Tiit Vunk of Estonia. Congratulations to both!


Rules Fill the cells with numbers 1 to 9, so that no number repeats in a row, column or outlined 3×3 square. Whenever a number is equal to the sum of some numbers in a diagonal direction, an arrow is placed pointing there.

(The standard rules also have arrows pointing horizontally and vertically.)

Puzzles 138-140: Not Oasis

I played around with what I thought were the rules to Oasis today, and came up with this variant.

Rules Shade some cells, to leave a connected area of unshaded cells that includes all given numbers and doesn’t cover any 2×2 square. Some shaded cells are given. Numbers indicate how many other numbers can be reached through unshaded, unnumbered cells.

Example (a poor example: shaded cells can be adjacent)notoasis-example

Puzzlesnotoasis-1 notoasis-2 notoasis-3

Puzzle 136: External Sudoku

We’re running a small preview series on croco-puzzle for the 2016 WSC and WPC, which will take place in Slovakia soon. We’ll kick it off with an External Sudoku tomorrow. For this, I made an example puzzle which seems worth posting in its own right.


Rules Solve as a standard Sudoku, i.e., fill the grid with numbers 1-8 such that every row, column and outlined area contains each digit exactly once.

In addition, there is a diagonal rectangle of gray cells. Every edge of this rectangle must contain exactly the digits 1-(length of the edge). Diagonally adjacent digits in gray cells must not be consecutive.

Or see the instruction booklet.