Daily League Sudoku #60: Doppelblock Sudoku

This is the second puzzle in the 'Latin Square Sudoku' Series. I've always liked this genre. Nine by nine puzzle are normally pretty hard to accomplish, but it's possible. Adding the regions makes it much easier to construct.

This variant is pretty similar to Between 1 and 9 Sudoku, except for the fact that you aren't forced to give a given. I tried to use an opening that takes the regions into account. This puzzle shouldn't be too hard. I actually had a harder version of this puzzle, but it was a bit too much in my opinion. I didn't even have an option to make it easier without ruining most of the puzzle. I hope it's fun.

[Edit: Puzzle fixed. I made an error, forgetting 7 could be a single digit sum.]

Rules for Sudoku

In this Sudoku you have to blacken two cells in every row, column and marked 3x3 region. Then you have to place the digits 1~7 once in every row, column and marked 3x3 region. Numbers on the outside indicate the sum of the digits in between the black cells in that row or column.




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Puzzle #180: Slitherlink; Filled Loop

This is the eighth practise puzzle for this year's UKPA Open.

This is what I feel is another inherently hard type. So I tried to at least create a few openings that were all based on purely Slitherlink logic. there is a point in the end usually where you aren't as free in choosing your Slitherlink clues as you still need to fit in all pentominos. I think in the end this one gets a bit harder, but if you take into account the "no three can meet" rule, you should still be able to work through.

Rules for Slitherlink

In this Slitherlink the loop has to be completely filled with the given pentominos. Each pentomino must be used exactly once. They may be rotated and reflected. Pentominos may only touch each other by a single edgNowhere do three or more pentominos meet at a point.

Example

Puzzle

Puzzle #179: LITS

This is the seventh practise puzzle for this year's UKPA Open.

If I've written more of the same puzzle type, I always find it hard to think of an opening. Usually in LITS I end up just putting down a few nice looking rooms and see if there's any interaction that I like. This combination of the letter LITS seemed to work for well. The end result worked pretty well, although it took a while to get it unique.

Rules for LITS

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Puzzle #178: Tapa; Triomino

This is the sixth practise puzzle for this year's UKPA Open.

In my TVC practise series, I have become pretty proficient in writing Tapa variants. Usually my puzzles are on the harder side. Thus is won't be overly surprising that this is also a bit of a harder puzzle. This puzzle has a single opening and it's important to find it as I don't think there is any other way through it.

Rules for Tapa

In this Tapa, you must be able to divide the wall into the given triominos.

Example

Puzzle



Puzzle #177: Nurikabe; Domino

This is the fifth practise puzzle for this year's UKPA Open.

This section came about because I wanted to include some common types, while still falling within the theme. I was familiar with three variants of common type that required division into polyominos. So this was easily collected.
I haven't seen that many Domino Nurikabes, so my first go was just checking out what I could do with the genre. The opening was pretty quickly set up. The middle and end game was where it gets tricky. It all works out logically, but it's not too obvious on first sight. It took a while to get the wall to behave properly.

Rules for Nurikabe

In this Nurikabe, you must be able to partition the stream into non-overlapping dominoes.

Example

Puzzle

Daily League #59: Skyscrapers Sudoku

For the month of February the theme will be Latin Squares Sudoku. This might sound like an odd name as every Sudoku is a Latin Square. But what I mean by this is that every Sudoku will be a Sudoku variant of a Latin Square logic puzzle.

The first one is a Skyscrapers Sudoku. Skyscrapers is one of the most used Latin Squares types. Pretty much every WPC I have been to has had at least one. It's a simple idea that can lead to a lot of different puzzles. I think it's the first time I've actually written a Skyscrapers Sudoku, although I have written many Skyscrapers. You can more easily run into unforeseen uniqueness issues with the Sudoku regions added. I had a few puzzles end up having no solutions. I had to tweak the layout a bit. I originally had 4567 on the left side and 456 on the right side, but nothing nice came out of that. The final puzzle should be fun to solve.

Rules for Sudoku

In this Sudoku digits represent Skyscrapers of that height. Clues on the outside indicate how many skyscrapers are visible in that row or column when looking from that side. Larger digits block the view of smaller digits.

Puzzle #176: Pentomino In A Box

This is the fourth practise puzzle for this year's UKPA Open.

Originally this was going to be Pentomino Areas. But when I remembered this type, I had the option to push that down to Tetromino Areas. The first puzzles of this type I've seen are form Richard Stolk. I always find them a bit tricky. I was a bit afraid including this type as I thought they might turn out too hard. I wrote a number of these puzzles and selected the two I thought were easiest. This is the hardest of the two because it has a bit narrower a path. It also felt a bit different than I normally encounter in this type. I thought this was actually easier than normal.

Rules:

Place the given pentominos in the grid so they don't touch each other, not even diagonally. Pentominos can be rotated and reflected. Each black-bordered region must contain three coloured cells that belong to two different pentominos.

Example

Puzzle

Puzzle #175: Tetromino Areas

This is the third practise puzzle for this year's UKPA Open.

The first time I wrote this was for the 2014 Polish Championship Team Round. It was a simpler variant of the more common Pentomino Areas. Originally I was going to use LITS for this type, but I liked that better in the second group. This was the second type I thought of. This puzzle is the harder of the two puzzles. Neither is overly difficult. If you see the opening of the puzzle it should cause no problems.

Rules:

Place the given set of tetrominos in the grid so that they don't touch each other, not even diagonally. Tetrominos may be rotated and reflected. Each black-bordered region must contain a single tetromino.

Example

 

 

Puzzle

 

Puzzle #174: Trio Cut

This is the second practise puzzle for this year's UKPA Open.

I saw this type the first time in the No Numbers test at LMI. I have good memories of it as that's the only test I have ever won. This puzzle is definitely the harder puzzle. The first one I played around a bit with how the type worked. For this one I tried to find a bit more tricky an opening and path. I think it worked out well.

Rules:

Colour some cells so that they form triominos. Each triomino must be cut twice by a black border. Different triominos must not touch each other by an edge. Each black-bordered region must contain exactly three coloured cells. Cells in the same region may belong to the same triomino.

Example 

Puzzle

 

 



Puzzle #173: Norinori

This is the first practise puzzle for this year's UKPA Open.

This is the first Norinori puzzle I have ever written. I wanted to avoid using a domino region as an opening. This is one of the two I found. It is also the harder of the two. This puzzle is pretty hard as there are some key deductions to be made in the middle. It wasn't something I had used myself in a Norinori puzzle before.

Rules:

Colour two cells in each black-bordered region, so that each black cell shares an edge with exactly one other black cell. Black cells may touch within a region, but don't have to.

Example

Puzzle

UKPA Open: Introduction

I wrote a set of puzzles for the UKPA Open 2016 held at Selsdon Park Hotel in Croydon this year. The championship will be held the 27th and 28th of February. The Sudoku tournament will be held on the 27th of February. The Puzzle Championship will be held in two sessions over the 27th and 28th of February. The championship is open to foreign competitors.

While writing this set, I wrote two puzzles per type and selected one to be included in the final set. I will be releasing all puzzles that were not included in the set as preparation. Most of these puzzles will be a bit harder than the actual puzzles in the set, but I figure any example is better than nothing. The puzzles will be posted from Monday through Thursday for the next four weeks.

The set I wrote was based around the numbers 2, 3, 4 and 5. It started when I was playing around with different types to include in the set. I was thinking of including Norinori, which uses dominos, as I'd never written one. Then I thought Trio Cut, which uses triominos, might be fun too. Then I thought there are also similar types that use tetrominos and pentominos too.
So I tried to find more types that are somewhat similar that use the same polyominos. Three groups I had quickly put together. The number place category was a bit harder. I couldn't really remember any types that use triominos or tetrominos to place symbols in. So I changed that group a little to types that use 1~2, 1~3, 1~4 and 1~5 instead as that was easier to establish.

I hope these puzzles are useful and the set enjoyable.

The eventual groups and types that were used are as follows.

Room Placement:

- Norinori
- Trio Cut
- Tetromino Areas
- Pentomino In A Box

These are all types that place polyominos by using rooms.

Split Wall:

- Domino Nurikabe
- Triomino Tapa
- LITS
- Filled Loop

These are all types where you create a wall (or loop) that needs to be split into polyominos.

Division:

- Dominos
- Sandwich
- L-Division
- Pentominous

These are all types where the grid has to be divided into polyominos of the same size.

Number Placement:

- Sum Sweeper
- Neighbours
- Magic Snail
- Capsules

These types use an increasing set of numbers.

Daily League #58: Odd's Neighbours Sum Sudoku

This is the last Sudoku in the Odd Sudoku series. This variant revisits last week's variant. This time the clues outside indicate the sum of the neighbours of the second odd digit. I thought that might make for an interesting variant.

This puzzle was harder to construct than last week's puzzle as you're giving less information about the neighbours. Finding a good opening wasn't all that easy, but this one works well. The whole design was a careful process. I ran in a few problems where there no longer was any valid solution left. The puzzle has a very narrow logical path, but I like how it all worked out. Don't expect this to be a fast solve, but it should still be fun. Enjoy.

Rules for Sudoku

In this Sudoku the numbers on the outside indicate the sum of the neighbouring digits of the second odd digit in that row or column, when looking from that side.

Click to enlarge

Daily League #57: Odd's Neighbours Sudoku

This is the fourth Sudoku in the Odd Sudoku series. It's a new variant called Odd's Neighbours Sudoku. It is similar to Next To Nine Sudoku. In this Sudoku, digits on the outside are the digits next to the second odd digit in that row or column. The second odd digit works the nicest in my mind, as the first odd digit has five single digit clues per side. I played around with a lot of similar ideas like this, but this was the one I thought worked the nicest. I actually think there's a lot of different things happening in this genre and it's one of my favourite variants I came up with.

It was a bit of trouble thinking of a nice opening, but I think this way works well. I figured out a few different openings, but this was the first I came up with. At the start I thought I would need a lot of clues to get this puzzle to work. But as I got through the opening I noticed I would need a lot less clues than I had at first imagined. I liked how the neighbouring digits worked together with the second odd digit rule. I think this was my favourite puzzle to design in the series.  I hope you enjoy it too.

Rules for Sudoku

In this Sudoku digits on the outside indicate the direct neighbours off the second odd digit in that row or column, when looking from that side.

Click to enlarge

Daily League #56: Odd Arrow Sudoku

This is the third Sudoku in the Odd Sudoku series. It is called Odd Arrow Sudoku. I haven't seen this variant before. It is a simple variant of Arrow Sudoku. In this puzzle the digit in the circle indicates the amount of odd digits along its arrow.

When first starting the design, I wasn't sure how to create a nice opening. I knew I had to have longer arrows to create an interesting puzzle as otherwise the possibilities in the circle would be too limited. After choosing this layout, I had a bit of trouble creating an opening. After a few tries, I had a nice opening. It wouldn't really become unique though. I could fix it with extra givens, but I'd rather not. When I added the arrow in the centre nonet, it allowed me to remove some givens to rework the end of the puzzle a bit. In the end this was the result and I think it's a nice solve. Enjoy.

Rules for Sudoku

In this Sudoku, a digit in a circle indicates the number of odd digits along its arrow.

Click to enlarge

TVC XVIII Practise: Part 2

This is the second part of the TVC XVIII practise set. This took a bit longer to prepare. Certain puzzles didn't want to become unique. Especially the Different Tapa took a while to construct. I think the average difficulty of this bunch is a bit higher that the previous part. This is partly because it contains more new genres, so it will take a bit of discovering the new knowledge in the variants.

The first puzzle is a Different Tapa. I took a bit of time to find a nice workable layout that didn't use the same shapes as the WPC puzzle and Robert Volmert's puzzle. I think layout looks nice and gave me enough room to place clues, while the shapes do interact. It took me a while to write this puzzle as I couldn't find a way to make it both unique and having a solution. In the end I managed to move 2 clues around, which finally made it unique. It's a tricky puzzle and you'll need to use the shape from early on in the solve to make progress.
The second puzzle is a Dissected Tapa. These are never too hard. Yin Yang is a good genre to practise for these puzzles.
The third puzzle is a Not Alone Tapa. I'm not sure about this genre. It seems very limiting as this 5 clue puzzle will show. For example, you can't have any T-shapes in the wall unless it's next to a clue cell.
The fourth puzzle is a Black Hole Tapa. I like the change that was made from the original instructions in the booklet. Having the count for the black hole and the amount of black holes both be variables can lead to completely different puzzle. I went for three black holes of value 2, which I think worked out well.
The last puzzle is a 4x4 Tapa. This puzzle somehow worked out this way with only 2 clues per 10x10 grid. There's a lot of things you need to take into account with this genre and I think this puzzle will help teach most of those things. It's important to think of the global picture to understand which deductions to make.

I hope all of this is helpful. Enjoy.

[Edit: wrong clue in Black Hole Tapa fixed]

Puzzles can be found below.

TVC XVIII Practise: Part 1

Here is part one of the TVC XVIII practise. It features five different variants. The second part will come out later tonight or tomorrow, depending on how much time I can find the rest of the day.

This post will contain the first five types in the instruction booklet. I managed to get through them in a nice way in order for once. Usually one type gives me some trouble.
First there is a Tapa With Borders. I decided to go for a 7x7 grid this time. I tried to avoid any wrong clues in the centre 4x4 square, so you couldn't directly work from there to find the grid.
The second puzzle is a Tapa-Like Loop. It's not really a Tapa, but it's a fun genre. The puzzle shouldn't be too hard.
The third puzzle is a Tapa LITS. This puzzle caused me the most trouble to make. I liked the layout, but it took some time to get a valid solution. Often I had areas that just wouldn't split up into tetrominos or it just wouldn't be unique. Eventually this came out.
Tapa Scrabble. I'm not much a fan of this type. Word puzzles are generally not my type anyway. I hope this puzzle is somewhat representative for the competition puzzles. I have the most doubt about this type.
Tapa Connection. This is probably the hardest puzzle in this set. This type is really restrictive. I wanted to see how far I could push it. Four clues with three pairs of letters gets you pretty close to the minimum I think for this size.

I hope the puzzles are useful. Enjoy.

Puzzles can be found below.

TVC XVIII Practise: Introduction

TVC XVIII is on this weekend. It will feature ten Tapa variants, five of which have not appeared in the TVC previously. These variants are Tapa LITS, Different Tapa, Not Alone Tapa, Black Hole Tapa and 4x4 Tapa.

Some examples of these new variants can be found online.

Tapa LITS:
Grandmaster Puzzles
A Cleverly Titled Logic Puzzle Blog (Streampunk/Tetra Firma)

Different Tapa:
Maybe Puzzles

This post will also contain some examples of the known variants that have featured on this blog below.

Puzzle #172: Tapa; Circled

This is the last of three posts with new Tapa variants for the TVC.

The last variant is Circled Tapa. It is based on Black and White Snake. As there is already a Black and White Tapa, I couldn't go with that name. My second thought was Dotted Tapa, but then I remembered Prasanna's Dotted Tapas. So lastly I settled on Circled Tapa, by just changing the wording of the rules. The variant here is that the Tapa wall is built up of alternating black and white circles. The clues indicate how many circles of a particular colour there are around it, instead of the number of coloured cells.

Rules for Tapa

In this Tapa the wall is made up of alternating black and white circles. There are black and white clue cells. White clue cells indicate the amount of white circles in the orthogonally connected sections of the wall around that cell. Black clue cells indicate the amount of black circles in the orthogonally connected sections of the wall around that cell. Each digit indicates a section of at least length 1.



Click to enlarge

Daily League #55: Odd Labyrinth Sudoku

The second puzzle in the Odd Sudoku series is an Odd Labyrinth Sudoku. I always enjoy solving these puzzles. It has a bit of puzzling in them, which always suits me well. You also get to create an odd/even grid, which is something I always enjoy. Parity variants always seem to suit me well.

In the design I tried to find some interesting deductions in this genre. If that totally worked, I'm not sure, but I had fun designing it. I didn't bother resolving any old puzzles, so it could be that this has been used before. It took a while to construct a valid puzzle though, as too often some of my logic led to no path existing. I think I lost some of the interesting things because I also had to make it unique, but it should still be a fun solve.

Rules for Sudoku

In this Sudoku there has to be a path that runs from the left top corner to the right bottom corner over cells that contain odd digits. This path can only travel horizontally and vertically.

Click to enlarge

Puzzle #171: Tapa; Castle

This is the second post of three new Tapa variants for the currently ongoing TVC.

This time the variant is Castle Tapa. This variant is based on the Castle Wall genre, hence the name. It also has some similarities to No Islands Tapa. There haven't been many variants that use different coloured clues. The rule is that all black clue squares are contained within the Tapa wall and white clue squares remain outside the Tapa wall. I now realise this is the exact opposite from Castle Wall, but I don't think it matters. The puzzle turned out well, in my opinion.

Rules for Tapa

This Tapa has black and white clue cells. White clue cells must always be outside the Tapa wall. You must always be able to reach the edge of the grid from them by travelling horizontally and vertically through uncoloured cells and/or clue cells. Black clue cells must always be inside the Tapa wall. You must not be able to reach the edge of the grid from them by travelling horizontally and vertically through uncoloured cells and/or clue cells.

Click to enlarge