Daily League Sudoku #5: Scattered Sudoku

This is my fifth Sudoku for the Daily Sudoku League. The last week so far has featured a Counting on Line Sudoku by Seungjae Kwak, an Equal Sudoku by Christoph Seeliger, a Between 1and 9 Sudoku by Prasanna Seshadri, a Fortress Sudoku by Bastien Vial-Jaime, a Little Killer by Rishi Puri and an Odd Sudoku by Tom Collyer.
This week I've gone for a simpler and more familiar variant. Scattered Sudoku is just a Jigsaw Sudoku with one non-contiguous region. The puzzle has only 17 clues, which is what I like about Jigsaw Sudokus. I like to get the amount of clues down to 20 or less, which is something I wouldn't get done in Classic Sudokus. The solve gets a bit trickier towards the end, but nothing overly difficult. It's in my opinion easier than the last two Sudokus I have posted. Hope you all enjoy them

Lastly, here is the latest PDF-file.
Week 5

Rules for Sudoku


This Sudoku has one non-contiguous 9 cell region, marked by the grey cells.

Puzzle #159: Capsules

This is a simple puzzle idea that can leave for really tricky puzzles. Most puzzles use similar techniques, except the way you employ them can make a puzzle far trickier. The grid size is a bit limited as the total number of cells has to be divisable by 5. But you can easily change certain sizes in nice ways to valid size. Leave out the center cell in a 9x9 grid, or the four corner squares in a 7x7 or 8x8 grid.
The last puzzle I post here was meant for a puzzle championship, but tested too hard, just like Tuesday's Ripple Effect puzzle. As this would be the first one I posted here, I added two extra smaller puzzles just to prepare people for the harder logic in the last puzzle. Both these smaller puzzles use a key part of the solving logic for the larger puzzle. Hopefully they help and you will enjoy all puzzles.

Rules for Capsules

Puzzle #1

 Puzzle #2

Puzzle #3

Rules: Capsules

Place the digits 1~5 once in every blackbordered region. No two equal digits can touch eachother, not even diagonally.

Puzzle #158: Ripple Effect

This is a puzzle originally intended for a puzzle competition, but testing came up with too high times so I'm posting it here now. I know it's different from my normal clueless ones, but there's a reason they were there. You might be able to figure out why later in the week. I think it still solves really nicely and has its tricky spots. A lot of the solve is very similar to my previous puzzles andthere is still a very directed path to the puzzle. I think I will always have trouble writing Ripple Effect puzzles that are more suitable for competition as there is a lot of fun logic to exploit, which is pretty tricky. I could of course put in far more smaller cages, except that is really not very fun to write for me. Anyways, enjoy the puzzle.

Rules for Ripple Effect

Daily League Sudoku #4: V-Day Sudoku

This week was Valentine's Day, which has influenced a lot of puzzles this week.
My Sudoku is inspired by the abbreviation for Valentine's Day, which seems to be used more often these days, namely V-Day. That's why my Sudoku is themed around the number 5 or V in Roman numerals. It's basically a simple variation of XV Sudoku, except I changed the X pairing of a sum of 10 to a pairing of a difference of 5. The only real difference in the solve is that you don't know whether a mark is a sum of 5 or a difference of 5. As a further theme, the givens spell out the date of Valentine's day: 14-2. For Americans who feel the date is written wrong, you could rotate the grid 180 degrees and spell out 2-14 in the same squares that are filled now and still solve it in the same way. The switching of the places for 1 and 4 doesn't matter and keeps the puzzle unique, but the solution does change a bit.
The puzzle is moderately difficult. Not too difficult, but you have to remember well that all hearts are given.

Rules for Sudoku

Everywhere two adjacent digits have a sum or a difference of 5 a heart is given.

Puzzle #157: Tapa Special

As I've mentioned before, each year I make a special puzzle for my girlfriend for our anniversary. Earlier examples include my Quattro Stagione and LITS Cube puzzles. This year I went for a big Tapa puzzle. It's her favourite puzzle type, so I thought I'd have a go at it. It was an ambitious project that didn't go without its problems. The first draft ended up having about 8 errors in various places. I eventually removed all but one when I had it tested, which brought about one last bad deduction on my part, which I had missed. Eventually I got it fixed and this is the result. My girlfriend is currently still working on it, but she gave permission to share it with you today.
I've made it available as a PDF through Google docs. This is because I'd advice printing it and I scaled it down in the pdf so it prints easily. It also includes all rules and the layout, to make the solving easier. It's a challenging puzzle and I think it helps being able to visualise the whole puzzle.

Below will be the same information as in the PDF, for anyone preferring to solve it on the computer. This includes a full size image. If there are any questions about the rules, please feel free to ask.

Polish Online Qualifiers: Magnets and Yajilin

The Polish online qualifiers were held December last year. You can find the puzzles and sudokus here: Puzzle Set 1, Puzzle Set 2, Sudoku Set 1, Combination Set. I'm not sure on the details what each set was used for as I can't read Polish. I contributed 2 puzzles, which can be found in the first Puzzle Set. They are a Yajilin and a Magnets puzzle. I tried to make them easy, but I was told after the testing that the Magnets puzzle still wasn't very easy. I seem to not able to write easy Magnets puzzles. I'm guessing some of the deductions just come standard to me but they don't come standard to others. They're both still nice puzzles, so hope you enjoy them too.

Rules for Yajilin

Rules for Magnets

Daily League Sudoku #3: Battenburg Sudoku

Last week I didn't provide a puzzle as Stefan Heine had a puzzle ready, so I gave up my Saturday spot. This week there is another Sudoku by me. This is a Battenburg Sudoku, which is a Sudoku type I came up with.  The name comes from the Battenburg markings, although it stays more in my mind for Battenberg cake, which is a checkerboard pattern. In this puzzle everywhere 2 odd and 2 even digits form a checkerboard pattern, a mark is given. The opening of the puzzle I have in mind is a bit puzzly and might trick up some Sudoku-solvers. That's why I have made a second puzzle that should help you realise part of the logic involved in the opening, which is posted here. I hope you enjoy it, it was fun to make at least.

Lastly I'll provide three links for the puzzle files of the last three weeks.

Week 2
Week 3
Week 4

Rules for Sudoku

In this Sudoku, everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given.

Click to enlarge

Puzzle #156: Battenburg

This puzzle is as preperation for my next Daily League Sudoku. I was a bit afraid part of the logic might trick up some people, so I figured I'd make something nice to practise it with. I think the puzzle turned out really nicely, with the asymmetric clues. It should be fun to solve, even though the logic might be a bit repetitive.

Rules for Battenburg

Place 5 black circles and 4 white circles in every row, column and marked 3x3 area. Everywhere 2 black and 2 white circles form a 2x2 checkerboard pattern a Battenburg marking is given. Some circles are already placed.

Daily League Sudoku #2: No Ten Sudoku

This is my second contribution to the Daily Sudoku League. This week so far featured a Killer Sudoku by Fred, a Queen Sudoku by Prasanna, a Diagonal Sudoku by Bastien, a Non-Consecutive Jigsaw Sudoku by Rishi and a Jigsaw Sudoku by Tom.
My puzzle will be a No Ten Sudoku. It is similar to Non-Consecutive and XV Sudoku, where no two neighbouring cells add to 10. It's a bit of a troubling type to design by hand as it's hard to judge in advance if you can still create a valid solution from this point on. This is also the reason it's almost impossible to design a Nonconsecutive Sudoku by hand. Usually they are designed with the help of a computer program, to make sure your currently set up Sudoku still has a valid solution. Too bad I didn't have a program to verify a solution for this variant. Although I usually design my puzzle progressively, I did create a valid solution first for this puzzle and then worked out how to turn that solution into a unique and logically solvable puzzle.

A little bit more on the league. We're using this Google Doc to keep track of the solving times. You can request access to it, even if you're not on facebook. You can add your name to the excel sheet and post your own times here for each puzzle. You can still add your times till a week after the end of a week to be considered for the Hall of Fame.
At the end of a puzzle week, Tom will create a Pdf with all puzzles of the week. This Pdf will contain the puzzles,  the best solving time and an estimated time for intermediate and novice solvers. The Pdf of Week 1 is available in the Facebook group or as a Google Doc. The Pdf for week 2 is currently only available in the facebook group.
In case you're interested in creating a puzzle for the Daily League, feel free to let us know in the facebook group. More constructors are always welcome.

Rules for Sudoku

In this Sudoku no two adjacent digits may add to 10.

Click to enlarge

Daily League Sudoku #1: Distance Sudoku

This puzzle is part of the Daily Sudoku League. It's league for Sudoku solvers to test their skills against eachother on handmade Sudokus. It features puzzles by Rishi Puri, Tom Collyer, Fred Stalder, Prasanna Seshadri, Bastien Vial-Jaime and Seungjae Kwak. I will also be contributing puzzles to the league. Each day a Sudoku will be posted in the group and on the blogs of the respective author. At the end of the week a PDF will be released with all Sudokus of that week. The league is free to enter for anyone by joining the facebook group. So if you feel like testing your solving skills against others, please join.

For my first puzzle in the league, I have chosen a Distance Sudoku. It's a type I always like to solve. I have never made one before. I would rate it hard, as I would rate most my Sudoku variants. The little bit of aestetic in the puzzle can be found in the fact that the digits are built up of 4 sets of 1~9. I think it worked out well and gives for a challenging solve. I'm hoping it's not too hard for the general level aimed at for the Daily League, but I will find out after the first people have solved it. It should be fun to solve either way.

[Edit: I adjusted the image to conform with previous puzzles]

Rules for Sudoku

Outside each row and column the distance between two digits in that row or column is given. The order of the digits is top to bottom and left to right.

Click to enlarge

Puzzle #155: Yajilin

This puzzle has an opening that I like. It's probably been used before by others as it fits very well in a standard grid size. I tried to keep it symmetric, but after working through a big part of the puzzle it wouldn't get unique symmetrically without sacrificing some of the previous logic. As I liked everything I had put in till that point, I went looking for a fun way to finish it. I think I acchieved what I wanted in the end. Hope you enjoy it too.

Rules for Yajilin

Click to enlarge

Puzzle #154: Turning Fences

Here's a 2013 inpired Turning Fences puzzle. You can find 2013 8 times in the grid. It's probably the easiest Turning Fences on this blog so far, so it's probably good practise for people new to this genre. When I had put all numbers in, it sadly turned out to have 8 solutions, but I really liked the way it looked. So I fixed it with a few crosses, just to make it unique. They don't change the solve in the slightest, so it seemed like an acceptable compromise. Enjoy.

Rules for Turning Fences

The loop can't go through crosses.

Puzzle #153: Shakashaka

Happy New Years to most of Europe and Africa. Gelukkig nieuwjaar voor alle Nederlanders.

Again this is the last post in the countdown. So here's a future new year's wish for people on a later time zone.

Happy New Years to the UK, USA and Canada when the time comes.

As last year, 0 was a tough option to do something with. As I didn't want to have repeat genres, I didn't want to choose Heyawake, which I thought would be the easiest option. Eventually I tried Shakashaka, as a 0 actually gives a lot of information in this genre.
The puzzle is pretty easy, just like last year's Akari. It's a good way to lead in the New Year.

0 - Shakashaka

Rules for Shakashaka

Puzzle #152: International Borders

Happy New Years India

As you might have noticed, this set contains far more new genres than my first set. I just wanted to avoid repeats of previous genres as much as possible. So I went on a long look through websites, looking for genres that might work with some of the numbers. From Palmer Mebane comes the puzzle type International Borders. During his LMI test, Puzzle Zoo, was the first time I came across it. I solved both of these puzzles during competition. I was hoping this genre would lend itself for a single digit puzzle, as it was different from most puzzle types. I first tried the number 0, but didn't like anything that came out of it, so I changed to the number 1. I found a simple opening and some interesting steps with only using 1's. I had to give in a bit to get it unique though. This isn't the best puzzle in the set, but I think it's still enjoyable. I might try this another time with more numbers, because it was pretty fun to try and design one of these.
It's probably and easy/medium puzzle. It might just take a while to get used to the genre.

1 - International Borders

Colour some squares without circles black, so that the grid is split into 2 seperate orthogonally connected areas. Circles of the same colour should be part of the same area, different colours should belong to different areas. Grey circles can be part of either area. Numbers in the grid indicate how many of the four orthogonally adjacent cells have to be coloured black. All black cells should share a border with both areas.

Puzzle #151: Sandwich

Happy New Years Indonesia and China

I went on the hunt for some puzzle genres I had never done for this set. One of the places this regularly leads me is of course Naoki Inaba's site. There seem to have been a few changes to his site. You can now copy all Japanese characters and some of the puzzle types have English translations added to it from the Naoki-Projekt on Logic Masters Deutschland. When I saw this type, I figured it could be a good genre to use the number 2 on. It took a while to get it unique. The opening is a bit standard, but in the end it gets a bit trickier, but there was no better way to force it unique. The name of the genre comes from google translate. It translated the puzzle name as "Santoitchi" but suggested I might mean the Japanese for Sandwich. It might have an alternative meaning but I got persuaded to just name it Sandwich. I have no real clue why it would called this though and I guess I could just stick with Santoitchi, as many Japanese puzzle types keep their original Japanese name.
The puzzle is medium/hard difficulty. There's a logic path to the end, but for a new genre it might be a bit trickier. It might help to try some of Naoki's at first.

2 - Sandwich

Colour some cells black, so that the remaining area can be split up into triminoes. No two black cells can share an edge. Each trimino must contain a number. A number indicates how many black cells share an edge with that trimino.

 

Puzzle #150: Lighthouses

Happy New Years Japan, South Korea and the rest of Australia

I tried a whole bunch of puzzle variants for the number 3. Slitherlink, Corral, Tren and Minesweeper were a few of the puzzle types. As I already had enough Loop Puzzles and not really any placement puzzles, I tried to find a genre that might work. Lighthouses was one of these puzzle types. The puzzle isn't very special, but I think it turned out okay.
This is an easy puzzle, probably the easiest in the set. Shouldn't take people too much time.

3 - Lighthouses

Place a number of 1 cell ships in the grid, so that no two ships touch eachother, not even diagonally. There are a few lighthouses in the grid. The lighthouses can see horizontallyand vertically. The numbers indicate how many ships can be seen in all four directions. No ships can touch the lighthouses, not even diagonally. Squares with water can't contain any ships.

Puzzle #149: Bosnian Road

Happy New Years Australia.

This is one of the new types to my blog in this set. I hadn't made any of these puzzles before this one. Again my first choice of digit worked out. I had seen Prasanna Seshadri make some good use of the number 4 in one of his puzzles, so figured this number might work. Took a while to get it right though as the number didn't let itself be unique that easily. It's the number which has the most possible configurations in this genre. It took a while to get the end right, but I thought the opening was really solid, so I wasn't going to give up on the opening and eventually i found a nice way to get it unique.
It's easy/medium difficulty. The opening is fairly standard, but it has a few trickier steps in the middle. Just for the fun of it, count the length of the loop in the end. It's purely coincidental, but I thought it was funny none-the-less.

4 - Bosnian Road

Draw a single closed  one-cell wide loop, that doesn't touch itself, not even diagonally. The loop doesn't go through clue cells. The clues indicate how many of the 8 cells around it are used by the loop

Puzzle #148: Tapa; Make Room for Pentapa

Happy New Years Samoa and New Zealand. 

The number 5 again had to be a pentomino puzzle for me. Last year's comined it with Nurikabe, where this puzzle combines it with Tapa. Other variants like Pentapa and Tapa Pentapool didn't really lend itself well for all 5 clues, but the added region constraint for Pentapa made it easier. I think it worked out well in the end and fits in well with the 5 theme this way.
This puzzle is again medium/hard. There's 2 important steps in the design, although the genre is pretty restrictive, so there might be other ways to the solution.

Rules for Tapa

Follow normal Tapa rules. Additionally, the Tapa wall is made up of 11 of the 12 pentominos (as the P-pentomino breaks a Tapa rule). Each blackbordered region contains exactly one pentomino.

Puzzle #147: All Seeing Snake

This puzzle came about after the For-Smarts Anniversary contest on LMI, where it was one of the puzzle types. I figured the rules had enough constraints to make a unique digit puzzle possible. As I needed a few puzzles with higher digits, I opted to try a puzzle with all 6 digits, as any higher would probably be too difficult. Played a bit with the grid sizes to see what would work best. Eventually this puzzle popped out. When I noticed it would have to be a 67 cell snake to make it unique, I opted to add an empty cell marked with an X, so the length would be 66 cells, as I thought that would fit in nicely with the 6 theme of the puzzle.
The puzzle is of medium/hard difficulty. Make sure to remember to make the Snake the right length.


6 - All Seeing Snake

Draw in the grid a snake of 66 cells. The body of the snake cannot touch itself, not even
diagonally. Numbers indicate how many segments of the snake are “seen” from this cell, not
counting the cell itself. Snake always makes a turn in the cells with numbers. The head and
the tail are not given and are subjects to determine. Cells with X remain empty.