Wednesday 30 May 2012

Puzzle #109: Camping

Yesterday's puzzle was scrapped at the last moment. the puzzle was not unique as I had made a flaw in the opening, so the whole puzzle didn't work anymore. There was really no saving it. I didn't want to just make a quick puzzle and instead moved the posting up a day.

This weekend I won my first LMI monthly puzzle test. I hadn't expected it when I finished it, with how disappointing the last 40 minutes went. In the first 80 minutes I had brushed off all puzzles besides the two "no numbers" genres. I thought it would be best to try to solve both No Number Field puzzles and leave the easy loop for the end. But after really struggling through that easy one, I quickly switched to the loop. The easy one I liked, although I struggled with it a little. I managed about half the second No Numbers Loop in the last 10 minutes. I made a mistake and it took me over 10 tries afterwards to discover what I was doing wrong.
Through Saturday it became clear though that I wasn't the only one who struggled with a few of the puzzles. In the end the top mostly solved the same puzzles, with the big difference being that I did manage to solve the second Synchronised Maze.

Today's puzzle is very old school to me. It was a standard puzzle in Breinbrekers when I first started buying the magazine. It has some similarities to Tents and Trees. The name of the puzzle was "Huisje, Boompje, Beestje" which is a Dutch saying that literally translates to "little House, little Tree, little Animal". The puzzle layout featured a house, a tree and a heart. Because the saying doesn't really translate to English in a way that it's applicable to a puzzle type, I changed the idea a bit. Instead it's represented by a camping ground.
When I first got the magazine this puzzle type always broke me up. I hardly ever managed to solve the puzzles. Then when I first started making puzzles, I tried making one of these. And all of the sudden I was able to solve them. It was the first time I noticed that trying to design a puzzle helps with solving a puzzle type.
There are 2 puzzles. One is a small easy one to help learn a few of the tricks involved. The second one is a normal sized puzzle. It's harder, but completely logically solvable. Hope you guys enjoy them.

Rules for Camping

Easy Puzzle

Hard Puzzle

Click to enlarge

Rules: Camping

Place a number of tents, trees and caravans in the grid. Each tree has a tent and a caravan orthogonally connected to it. No two equal symbols can touch eachother, not even diagonally. The numbers on the outside indicate how many of each symbol are in that row or column.

Thursday 24 May 2012

Puzzle #108: Not Alone

While creating the Black and White Matchmaker as a practise puzzle, I discovered an interesting logic deduction regarding the "Not Alone" puzzle type, which I thought could lead to an interesting puzzle and severely reduce the amount of clues necessary to make it unique. So I tried it and brought it down to only 10 clues. I'm not convinced this is the minimum, but it's far fewer than I thought at first. At first the puzzle reminded me of the Binary puzzles, which are now also published here in a seperate booklet, which I find a boring puzzle type. But this rule is actually far more interesting that those puzzles. This one was pretty fun to create. I wonder how it will be perceived as difficulty. If you realise the one logic deduction I exploited here, it shouldn't be too hard. When you don't realise it, I don't know how people will feel about it.


Fill the grid with black or white circles so that each row or column has the same amount of black circles and white circles. One circle of a color can't be sandwiched by circles of the other color horizontally or vertically.
An array of two or more circles of a same color may be sandwiched by circles of the other color  horizontally or vertically.

Wednesday 23 May 2012

No Number Practise: Black and White Matchmaker

This weekend is the No Numbers test at Logic Masters India. It is written by Ko Okamato (Xevs). It contains  only puzzles without numbers in the grid, Most types are new to everyone, although I have come across Synchronised Maze before. It might not be my best performance as some of the types are a bit prone to error. The 2 "No numbers" puzzles have to be approached very carefully as it's easy to accidentally leave a number in when you make a small transcription (No Numbers Field) or reading (No Numbers Loop) error. Prasanna created practise puzzles for the other puzzle types, which can be found here, here and here.

I decided to make a Black and White Matchmaker as practise. I've never been any good at these matchmaker type puzzles. I tend to just avoid them unless it's the only one left. In this test it's over a quarter of the points, so probably wise to attempt. Also it contains the most familiar puzzle types. So I figured it would be worth a try to design one so I could find some easy ways to exclude certain types from certain puzzle grids. I've put in a few of ways I found in the grids. The puzzle turned out okay, but with a bit more effort I could have probably made the puzzles overlap in a few more genres.

I've put all puzzles in a single image with a table to match the puzzle types. I also have all puzzle grids as a seperate image. If it would be preferred that I post them all seperately, I can do that as well.

General Rule

There are 6 puzzle grids given with black and white circles and 5 puzzle types. Match each type to one puzzle grid and solve it under that rule. One of the grids won't be used. Certain grids might be solvable under multiple rules, but it's only possible to match them in one way so all 5 rules can be solved in a seperate grid.

Puzzle Types

Draw a single loop that runs horizontally and vertically though every cell with a circle. In cells with black circles, the loop must make a 90-degree turn and go straight in both neighboring cells. In cells with white circles, the loop must go straight and makes a 90-degree turn in at least one of neighboring cells.

Black & White:
Fill the grid with black or white circles so that all of the circles with same color will be connected vertically or horizontally. Circles with same color can't form a 2x2 square.

Sun & Moon:
Draw a single loop that runs horizontally and vertically through every cell in the grid once. The loop can't make turns between cells with circles of the same color, and makes just one 90-degree turn between cells with circles of different colors.

Not alone:
Fill the grid with black or white circles so that each row or column has the same amount of black circles and white circles. One circle of a color can't be sandwiched by circles of the other color horizontally or vertically.
An array of two or more circles of a same color may be sandwiched by circles of the other color  horizontally or vertically.

Signal loop:
Draw a single loop that runs horizontally and vertically through every cell except cells with black circles. The loop goes straight in cells with white circles.

Click to enlarge

Tuesday 22 May 2012

Puzzle #107: Blind Spot

Here's another genre taken from Naoki's website. Although I think I've seen it before somewhere else as well. It just seem familiar from a few years ago. So possibly it featured on a WPC at one point.
 The first puzzle I made I liked a lot, except I thought it was a bit too hard as the first one on my blog. So I made another one, which was much easier. But I figured I need something a little bit more challenging to post. So I made a third one, which fell a bit in between both puzzles. And instead of posting just one, I'm going to post all 3. If you solve the example and then the first 2 puzzles in order, you should gradually get all the insights to also solve the third puzzle.

Rules for Blind Spot

Easy Puzzle

 Medium Puzzle

 Hard Puzzle

Rules: Blind Spot

This genre was developed by Naoki Inaba

Place an arrow for all four directions (up, down, left right) once in every row and column. No arrow points at another arrow. Black walls block the view of an arrow.

Saturday 19 May 2012

Puzzle #106: Killer Sudoku With Hidden Cages

This puzzle was inspired by a question raised on a sudoku forum if the Sunday Telegraph's Killer Sudoku With Hidden Cages was also solvable without the constraint that the number was always in the top left cell of the cage. It was never succesfully answered as those killers are probably meant to be solved that way. The Top Left cell constraint is a very powerful one, so it would probably not be unique. From here I figured it might be interesting to try to design a puzzle without that constraint. I'm guessing it's been done before, but I can't directly recall any of them.
I really like how the puzzle turned out. It looks nice and solves really smoothly. The opening probably isn't the most obvious one though. I don't think it's overly hard, but most of my Sudokus turn out a bit on the harder side. I think it's just something that automatically happens when I create Sudoku variants as I like to exploit and explore the opportunities a variant offers. Hope you all enjoy it.

Rules for Sudoku

In this Killer Sudoku the cages are hidden. Each cell with a clue number is part of a seperate cage. Each cage consists of orthogonally connected cells. The number indicates the sum of the digits in those cells. No digit can repeat within a cage. Cages consist of at least 2 cells. No two cages can overlap.

Thursday 17 May 2012

Puzzle #105: Quattro Stagioni (Corral, Nurikabe, Tapa LITS)

I have made a bunch of puzzles for friends for various reasons. Mostly for special occasions. I usually try to theme them in a certain way. This is mostly just based on the way the givens are oriented. For this puzzle though I had the fortune to get three handy numbers to work with, namely 2, 3 and 7. The numbers were handy to build into most genres, so I attempted to use them as best as I could. This puzzle is built up of four quadrants that each belong to a different genre. I thought a while about a good fourth genre to add as Nurikabe, Tapa and LITS have a similar general puzzle idea behind it. I couldn't come up with a good fourth genre that used this type of clue. So I cheated a bit by using corral-like clues, within the same puzzle structure. I think the puzzle worked out well, not overly difficult but still interesting.

Quattro Stagioni

General Rule:
Colour some cells to form a single contiguous shape. The shape doesn't form any 2x2 squares anywhere.

Left Top: "Corral"
The numbers in this section are all part of the shape. The numbers indicate how many cells that are part of this shape can be seen from this shape in horizontal and vertical direction, not including the cell itself. The numbers can't see past white cells. [Note: This section doesn't work like normal Corral. The clue type doesn't include the cell itself. Also there's no loop constraint.]

Right Top: Nurikabe
The numbers in this section each indicate a seperate island of orthogonally connected white cells. The numbers indicate the size of the island they are part of. All remaining cells in this section not part of an island belong to the shape. The islands can cross the border of this section.

Left Bottom: Tapa
The numbers in this section indicate how many consecutive cells are to be coloured around it. If there is more than one number in a cell, then each section of consecutive cells must be seperated by at least one empty cell.

Right Bottom: LITS
In this section colour 4 orthogonally connected cells in every boldbordered region. Two identical shapes in different regions can't touch eachother by a side. Rotations and reflections are considered the same shape.

Click to enlarge

Tuesday 15 May 2012

Puzzle #104: Yajilin

I had a pretty good weekend solving sudokus. I finished 13th in the Swiss championship, finishing all puzzles within the set 2 hours. I knew I wouldn't at all be close to the top solvers, so just happy I finished all. I had a lot of trouble with the half squares sudoku and messed up the thermometers on the first try. Although when I recognised my mistake I could just use the second option and the solve was far easier than purely logical.
My Sudoku 8x8 solve leaves me with a bit of mixed feelings. On the one hand I equaled my best performance in an LMI Sudoku test, on the other hand I screwed up in both parts and could have possibly gotten my first top 10 finish. In part A I made a few transposition errors in the Foursome Sudoku, leading to digits in the wrong place and thus having to restart even though the grids I had solved at that point were correct. In part B I wasted my first 20 minutes breaking the Skyscraper, Irregular without regions and Irregular Cube and only finishing the Cube in the end. When I finally got going, I managed to brush off 10 more puzzles in the remaining 44 minutes, but it could have all been far better. But in the end I did as well as I had hoped for both tests.

Now about today's puzzle. On May 10th there was a sudden spike of blog visits, which coincided with the arrival of my latest Akil Oyunlari magazine. This issue featured 4 Yajilin and 4 Tapa puzzles by my hand. Most visits to my blog that day featured my Yajilin pages. So from that I'm guessing people liked them and wanted to try some more. I do think that my Yajilin puzzles on my blog have generally been well received, so I decided to post another one for that reason today. This one is a bit larger than my normal ones, but not as big or challenging as my previous oversized Yajilin. I do think it's again a nice layout of givens, so enjoy.

Rules for Yajilin

Click to enlarge

Friday 11 May 2012

Puzzle #103: X Sums Sudoku

It's been a while since I've posted. This is mainly just through lack of inspiration on my part. I hadn't written any puzzles for the last month or so.  I recently wrote a bunch again and that went off pretty well, so I'm going to start posting puzzles again.

If you like Sudokus, this weekend can be an enjoyable one for you. With 2 Sudoku tests running, there is plenty to solve. Firstly there's the 8x8 Sudoku Contest on Logic Master India. This competition has 2 seperately solvable parts to it. Both parts have a variety of different 8x8 sudokus in it. One part with regular 2x4 nonets. In the second part the puzzles all have an abnormal layout, either irregular cages, or differently placed 2x4 cages.
There's also the Swiss Sudoku Championship hosted on Logic Masters Deutschland. This is a collection of mostly well known variants. It has a halved squares sudoku in it, which featured in its own round at the WSC in Hungary last year.

This Sudoku will feature in the LMI test. It's an interesting genre, which has some overlap with my own Frameless Sudoku. This idea though needs far fewer clues to get unique though. I am not sure if the puzzle in the championship will also look like this, but I think it's nicer by leaving clues out.

X sums sudoku

Fill in the whole grid with numbers 1-8 so that each number appears exactly once in every row, column and blackbordered area. Numbers outside the grid indicate the sum of first X-numbers in corresponding direction. Number X is always the first number in corresponding direction. F.E. - if the first number in row is 5, the outside number indicates the sum of first 5 numbers in that row.