Puzzle #82: Yajilin

Happy New Years India

I know, I'm over 2 hours late, but they crossed into 2012 18 minutes after my last post.

Yajilin was the obvious choice for me for the number 1. It's a genre that never uses very high clue numbers in a small grid. It took some effort to get a good puzzle out of it that was also a bit challenging.I think it's representative of some of my earlier Yajilin puzzles, even though there's no nice symmetrical layout this time. It's still a good solve of medium-hard difficulty.

1. Yajilin

Colour some cells so that you can draw a closed loop through all remaining white cells. The numbers in the grid tell you how many coloured cells can be seen in the direction of the arrow. No coloured cells are allowed to share an edge.

Puzzle #81: Liar Loop

Happy New Years Indonesia and China


Liar Loop was my first go to for the number 2 and it worked out well. I had been trying to make Liar Loop puzzles without the number 1 for a while, but I never got any good result out of it. As it always led to having to use a high amount of 2s to counteract the missing 1, I figured it should be possible to create one with all 2s. It took a lot of tries to get it to be unique though. It was very common to end in a situation where you'd either have a non-unique puzzle or were forced to use a section of 2 in an area.
The resulting puzzle is of medium difficulty, although it is probably harder if you haven't done the genre before. Check out some of the others on my blog if needed. Very little chance you'll encounter these anywhere else.

2. Liar Loop

Draw a closed loop through all squares by running horizontally and vertically. The loop doesn't touch or cross itself. The numbers in a boldly marked area indicate that the loop never runs through this many cells consecutively. Whenever it passes through the area it always runs through either more or less cells than the given number.

Puzzle #80: Double Back; Triple Back

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

At least this time I might actually be addressing multiple readers.

For the number 3, Double Back instantly sprang to mind. I had already done it with different numbers in my Four Colour Loop puzzle. I'm not the first to do Triple Back, as it has appeared on Palmer Mebane's blog as well. I like how this one turned out. I think once you get started with this puzzle, it shouldn't cause too many problems.

3. Double Back; Triple Back

Draw a single closed loop through all cells in the grid.  The loop must pass through each boldly marked region exactly thrice.

Puzzle #79: Tapa; Total 4

Happy New Years Australia.

I know, it's not New Years in all of Australia yet. Countries with multiple time zones are annoying.

I thought 4 would be a nice number to use in tapa. I tried to make a Maths Tapa with operations. But I realised that with only 4s, I had a lot of trouble creating openings. So instead I changed it a little and basically turned it into a mix between Tapa and Killer Sudoku. It doesn't add very much to the genre as many of the clues can be figured out instantly. I still like how the puzzle turned out though. Medium difficulty. Figuring out the opening is probably hardest.

4. Tapa; Total 4

Colour some cells to create a single contiguous shape. The shape can't have any 2 by 2 coloured areas. The clues in the grid tell you how many consecutive cells around it have to be coloured. If there's more than one digit in a cell, the groups of cells have to be seperated by at least one empty cell. Cells with clues remain empty.
Additionally, replace each question mark by a positive integer. Each clue square has 4 squares coloured around it.

Puzzle #78: Nurikabe; No Repeat.

Happy New Years Samoa and New Zealand.

I am almost 100% sure people aren't reading my blog there, but as they are the first, I figured i'd include them.

I don't think there is much of a surprise that this puzzle incorporates pentominos. I've always liked pentomino based puzzles. I think it is because the logic puzzles allow me to actually pack all 12 pentominos. This was one simple puzzle that stumped me a lot when I was young.
At first this was going to be a Shape Nurikabe, which Thomas Snyder used in his 20/10 Decathlon. Except I ran into the problem that it is pretty hard to fit 12 pentominos in a grid and create a valid Nurikabe grid. As I didn't manage to even create a valid grid, I changed the puzzle a bit. Instead I just went for no 2 islands having the same shape. this made things easier for me. The puzzle is of medium difficulty.
Also, if someone has a good suggestion for a name, I'm completely open for it.

5. Nurikabe; No Repeat

Determine for each cell if it's part of the stream or an island. Each number is part of a single island of horizontally and vertically connected cells, which size is equal to that number. Islands can't touch eachother horizontally or vertically. The cells not part of an island form the stream. The stream is a single connected area, which doesn't cover any 2x2 areas anywhere.
Additionally, no 2 islands have the same shape. Rotations and reflections are considered the same shape.

Puzzle #77: Heyawake

This was for a long time going to be a Ripple Effect or Country Road puzzle. But I didn't manage to do with either what I was aiming to do. Then I went to Heyawake as big clues can appear in a limited number there. I tried a few times and this was the nicest that came out of it. This puzzle is of medium hard difficulty. The 6 areas can't be determined quickly, but some deductions can be made to solve the rest of the puzzle, till finally the 6 areas also fall.

6. Heyawake

Paint some cells black. Black cells are not allowed to touch eachother on the sides. The remaining white area has to be connected. The white area can't span more than two consecutive rooms in a single row or column. The numbers in the rooms indicate how many cells are to be painted black.

[Edit: Another uniqueness issue fixed; it's not turning out as a good display of my construction skills]

Puzzle #76: Arrow Sudoku

Even though it's supposed to be a lucky number, it didn't bring me much luck in construction. I've tried using this number in numerous genres, but none of them really worked out. I wanted to add a second Sudoku puzzle and I went to Arrow Sudoku as I always enjoy them. It still took a long while to find a nice layout which could use only 7 clues. I'm happy with the end result. Difficulty-wise I find it hard to say, but I would call it challenging at least.

7. Arrow Sudoku

Place the digits 1-9 once in every row, column and 3x3 area. The digit in each circle equals the sum of the digits along its arrow. Digits are allowed to repeat along an arrow as long as it doesn't conflict with standard Sudoku rules.

Puzzle #75: Island

On first thought I was planning to make number 8 a Ken Ken puzzle. The problem is that I am not very good at making nice ones. After trying to find something else, I turned to Island. I figured all the same numbers for an Island puzzle could be interesting. I think the result worked out nice. It's probably the easiest Island puzzle on this blog so far, so I'm hoping people will appreciate the genre a bit more with this one as the difficulty of the previous ones has broken up most people so far. I guess I need to find a better way to judge the difficulty of these puzzles. I figured it was a relatively simple idea I used, but I think it wasn't.

8. Island

Fill in some cells to form a single island. The cells with numbers are part of this island. The numbers indicate how many unnumbered cells can be reached from that cell by moving horizontally or vertically. Numbered cells block access.

[Edit: Fixed Uniqueness issue)

Puzzle #74: Anglers

It took me a while to find a genre to satisfactorily apply the number 9 to. After going through a bunch of puzzle tests and puzzle sites I stumbled across Anglers. I've always liked Anglers puzzles, so it seemed like a good type. It worked out well. The puzzle isn't too hard.

9. Anglers

The digits on the outside represent anglers. Each angler catches one fish. The digit indicates the length of their line. The lines run by connecting the centers of cells horizontally and vertically. They don't touch or cross eachother.

Puzzle #73: Killer Sudoku

This puzzle is the one that started the whole idea of the count down. I was trying to make a Killer Sudoku with all the same sums. When I had seen a few people post a Christmas contest this year, I figured I could make a nice New Years countdown set. That's when I focussed on making one with all 10 cages.
I had first tried to make one with 1-9 but i couldn't get that right. When I attempted it with 0-8, it instantly became more productive. This puzzle is on the harder side, but I don't think it will stump the better solvers.

10. Killer Sudoku

Place the digits 0-8 once in every row, column and 3x3 area. The numbers in the dashed area indicate the sum of the digits in that area. No digits are repeated within any dashed area.

New Years Countdown

I´m sorry I haven´t been very active lately. It´s been a busy few weeks around the holidays. But I´m making up for it tomorrow.
I´ve seen some blogs feature a Holiday and Christmas special. This inspired me to write a series of puzzles as a New Years Countdown. The puzzles will be posted on regular intervals throughout the day, starting tonight at midnight CET and finishing at the start of 2012 CET.
So for those who have some time left over tomorrow, I hope you can enjoy some of these puzzles. For those who don´t, which I can completely understand, I hope they are a nice start to 2012.

Puzzle #72: Seethrough

I've seen this genre under a variety of other names: Doors, Walls, Open Office. I'm using this name as that is what I've always known it under. It was called Doorkijkje in Breinbrekers.
This puzzle was inspired by a particularly nice puzzle at the WPC. It appeared in the Evergreens round and was atypical for this genre (like all puzzles in that round). That puzzle contained only the number 1 as clues. This one has numbers 1-3, but the logic involved is very similar to that one. I think this is a more challenging puzzle to solve though.

Rules for Seethrough

Rules: Seethrough

Draw some walls inbetween the squares. The numbers in the squares indicate the total number of squares visible in horizontal and vertical direction from that square. There can be no isolated squares. This means that you should be able to reach all squares by moving horizontally and vertically.

Puzzle #71: Ripple Effect

I've always liked small challenging puzzles over large puzzles. I usually don't see much in a large puzzle that couldn't have been put into a smaller puzzle. I tried working on larger Ripple Effect puzzles, but I didn't seem to really be able to put anything in them I couldn't fit in a smaller size. So this one is a bit smaller than my previous ones but still challenging.

Rules for Ripple Effect

Puzzle #70: Tapa; Double Back

This is a new Tapa variation as far as I'm aware of. I had tried this idea before, but had trouble getting it to work. I now tried to it again and now understand how to make it work. I think the idea works very nciely now and brings some different logic to Tapa.
As the name suggest it has a similar idea as Double Back, but then in the Tapa format. The Tapa has to visit every region twice. Hope you enjoy it.

Rules for Tapa

Standard Tapa rules. Additionally, the Tapa has to visit every black bordered region exactly twice.

Puzzle #69: Four Colour Loop

This puzzle is a unique mix of four different genres: Maxi Loop, Liar Loop, Double Back and Country Road. I haven't ever seen genres combined in this way before. I've combined them by using the Four Colour Theorem. This theorem states that when a plane is split up in different regions, you'd only need four different colours to colour all regions without having any regions of the same colour touching by a side.
I'd been thinking of using this for a while, but it was hard to find a good set of puzzle rules that would work in a single puzzle. When I finally had four rules I thought would work, it took a while to even get a solid opening that would get the puzzle going. It took me a long while to get a good puzzle. I had to edit the puzzle a bunch of times as I kept running into mistakes I had made while constructing. I've worked on this puzzle on and off for a few weeks. I hope you all enjoy it. I'm warning you that it isn't easy, but it is completely logically solvable. It will probably take a while to see how the rules interact and what restrictions there are to assign the right rules to the right regions.

Four Colour Loop

General rule: 
Draw a single closed loop by connecting the centres of cells horizontally and vertically. The loop doesn't touch or cross itself. The grid is split up into different regions. Each region obeys one of four rules. No two regions with the same rule touch eachother by a side anywhere. They are allowed to touch by a corner.

Region rules:
Country Road:
The loop enters and exits the region once. The number in the region indicates the amount of cells the loop runs through. (Note: This means the loop doesn't run through all cells in the grid)

Double Back:
The loop runs through all cells in the region. The number in the region indicates the amount of the times the loop enters and exits the region.

Liar Loop:
The loop runs through all cells in the region. The number in the region indicates that the loop never runs through this many cells consecutively when traveling through that region. It is always more or less.

Maxi Loop:
The loop runs through all cells in the region. The number in the region indicates the highest amount of cells the loop runs through consecutively when running through this region.

Click to enlarge

Puzzle #68: Shakashaka

The first time I encountered this genre I really didn't get it. I had no clue how to approach it, let alone solve it. It wasn't till I encountered a puzzle on Mathgrant's blog, which had the four triangle layout that I managed to get a hang of it. I still find it funny how something cimple as a different layout or a different notation system can completely change your experience of a puzzle type.
When I understood how to work the genre, I started noticing it was actually a really fun genre. I hadn't encountered this kind of logic in any genre before. I've been working on a few puzzles. I find it hard to make nice flowing puzzles sometimes. I don't find it hard making really hard puzzles though. I've already discovered some interesting patterns that can be exploited. This puzzle is a bit easier though. It flows a bit more naturally.

Rules for Shakashaka

Rules: Shakashaka

This genre was developed by Nikoli.

Colour triangles in some squares so that the remaining white space are all shaped like rectangles. The triangles have to split a square into two equal size rightangled triangles. The numbers in the black squares indicate how many of the four adjacent squares are to be coloured with a triangle.

Puzzle #67: Slitherlink

And this is the last puzzle that featured in my set of the 24 Hour Puzzle Championship. Somehow I don't see many people being surprised that it is a Slitherlink puzzles. This has always been one of my favourite genres. It just seems to work well with how I like to solve and design puzzles. I decided to make this one on the easier side. A lot of familiar patterns and short term inner loop deductions. It was one of the lower scoring puzzles in the test and meant as a nice opening puzzle to the test.

Rules for Slitherlink

Puzzle #66: Liar Loop

So, this genre was developed while making this set. I was originally planning on putting in a Maxi Loop puzzle. But that ended up turning into a new genre. I was really happy with how the genre and the puzzle turned out. The test solving got positive feedback as well, so I figured I'd have a good new type. I first thought of keeping the genre only to the 24 hour puzzle championship, but as I had fun designing them I decided to just make one for the forum too. That way someone who followed my blog got a little advantage in the championship. That might be a tad unfair, but following my blog should be worth something.
This puzzle can also be used to get some practise in with Liar Loop solving. This will be handy for the puzzle that I will be releasing for Sinterklaas on monday. It's my present to you. It was originally planned as puzzle 50, but I didn't come close to acchieving that in the amount of time I had.

Rules for Liar Loop

Puzzle #65: Penta Sum

This is one of those standard genres for people who solve the Dutch magazine Breinbrekers. I always like them. And as it added come arithmetic to the puzzle set. I had never actually designed any before. I wanted to make it so there were no equal adjacent digits in the grid, in which I succeeded. Obviously I went for a sum of 24 for this puzzle. I though the grid layout made the place to start obvious, but I don't know you all will agree.

Penta Sum

Divide the grid into the 12 pentominos. The 5 digits in the pentomino must add up to 24. (The example uses tetrominos and the sum is 10.