Tag Archives: medium

Puzzle 136: External Sudoku

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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.

sudoku-aussen

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.

Puzzle 128: Pentomino pipes

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Here’s something new, a puzzle I made when a friend asked for “something with pipes”. I think the general idea of finding a pentomino net works quite well, though I’m not convinced of the details of the mechanics in this version. In particular, some other kind of clues might work better, e.g., giving the connection dots.

Edit Amended the rules to hack the puzzle to uniqueness.

pentopipes

Rules Place a full set of pentominoes onto the grid lines. (Each pentomino cell maps to a vertex, and adjacent vertices are connected by an edge, like the clues from Puzzle 82.) Each edge may be part of at most one pentomino. If two pentominoes touch at a vertex, there must be exactly two pentomino edges touching that vertex. There must not be any vertices with a single edge.

Wherever a vertex is marked by a letter, that vertex must be one of the five vertices of the pentomino corresponding to that letter. There may be still be a second pentomino using that vertex.

Pentominoes may be rotated and mirrored. Except F: F may be rotated but must be oriented as in the example solution.

Example with pentominos F, U, V, Y.

pentopipes-example

Puzzle 123: Countries

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Countries is another type from the Russian GP that I first saw in Budapest this year. This one should show that some of the deductions that seem almost correct aren’t always.

You might want to resolve it with full clues to get something more like the GP puzzles, though I suspect that that bypasses quite a bit of the logic.

Edit Fixed an ambiguity (second try), thanks Neil!

countries-1
Rules Subdivide the grid into orthogonally connected areas (“countries”), each containing exactly one letter. Numbers outside the grid give the number of cells in that row or column that are part of the first country in that row or column.

Or see the instruction booklet.

Puzzle 121: Yin-Yang Fences

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The next GP round is coming up, with the Russian GP authored by Andrey Bogdanov. One of the types is Yin-Yang Fences, which I first saw on Andrey and Vladimir’s round for the Budapest 24 hours this year. You should be able to find these here. Berni made another for our croco 24h review series.

You can leave out one of the 2s on the outside if you want more of a challenge.

yinyang-fences-1

Rules Solve as a standard Slither Link. In addition, all cells outside the loop must be connected, and there must be no 2×2-square of cells that is entirely inside or outside the loop.

Or see the instruction booklet.

Puzzle 120: Hochhausblöcke

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Some more Hochhausblöcke. In other news, the 10×10×10 series on croco-puzzle continues, and I submitted a few puzzles to the excellent puzzlepicnic, including a Fences puzzle where I’m curious to know if people find the intended break-in, and a Yajilin.

hochhausblock1

Rules Place numbers from 1 to 4 in each cell so that each row and column of each 4×4-block contains all numbers 1 to 4. Circled numbers are valid skyscraper clues for the adjacent grid (for both adjacent grids in the central corners). Uncircled numbers are not valid skyscraper clues for the adjacent grid (for neither adjacent grid in the central corners).

Puzzle 119: Skyscrapers (with parks)

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Here’s a skyscrapers puzzle. This is from a batch of puzzles I recently made for a series on croco-puzzle, consisting of 10 puzzles on 10×10 grids. I thought it was a nice opportunity to try my hands at making a large skyscraper puzzle, after some failed attempts in the past. The difficulty turned out such that it didn’t really fit with the rest of the series, so here you go.

Buildings of size 1-9 and one park (gap, invisible) per row and column.

skyscraper-gross-1

Puzzle 110: Greater Wall

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The next round of the Puzzle GP takes place next weekend, with the Dutch round authored by Bram de Laat. The instructions are out; it turns out Maxi Loop is one of the types (see Puzzle 91 and Puzzle 109), so we’ve got that done. One of the less familiar types is Greater Wall, compare Bram’s set for the Polish championships. The presentation has been much improved, with explicit placeholders. Here’s one.

greaterwall

Rules Shade some cells to form a wall that is connected by edge and doesn’t contain any 2×2-square. Where given, clues outside indicate all connected blocks of shaded cells in the corresponding row or column, in the correct order. Relations between two placeholders apply to the lengths of the corresponding blocks.