Sunday, 25 November 2018

World Puzzle Championship Puzzles - Round 12

The last set of puzzles are from round 12. This was the innovative round. There were a few types in there that were interesting to write. My favourite two types were Inner ABC and Coral with Letters. I think those are also the nicest puzzles in this set. One rule that popped up a lot in this championship was the "Worms" rule of alternating higher and lower digits within a path of numbers. It's probably not a rule that will be used much in the future. It didn't really strike me as a rule that added much to any of the puzzles.

Saturday, 24 November 2018

World Puzzle Championship Puzzles - Round 6

Round 6 had puzzles that were all combinations of different types of puzzles. There were some interesting ideas, but I doubt many of these will be seen more often again in future puzzle sets.

There's a few puzzles in here that I'm pretty happy with. The Starwacky puzzle is a nice solve. Snail on Snake worked out pretty well because it didn't need any extra given numbers, except for the head and tail. Galaxies and Tetrominoes is my favourite in the set, because it really forces the two types to work together.
The other puzzles should also be nice to solve.

Friday, 23 November 2018

World Puzzle Championship Puzzles - Round 3

I wrote a number of practice puzzles for myself, to help prepare for the World Puzzle Championships this year. I didn't have as much time to prepare, but it helped in the long run. Some people wanted to see them afterwards, so I promised to post them all on my blog.

I only really made puzzles for three rounds on the championship: Round 3, Round 6 and Round 12. This post contains puzzles from Round 3.
Most puzzles were overall a bit harder than the puzzles at the actual championship, because I took a bit more liberty with the design of most puzzles, especially in the amount of clues given. One puzzle ended up being broken, but I guess it still helped in a way to find out the logic in the genre.
For examples, please check the WPC instruction booklet.

Sunday, 8 October 2017

WSC Practice #9: Round 12 - What Is It?

This is the 9th practice puzzle for the 2017 WSC.

These are the last 2 practice puzzles for the WSC. I'll be focussing on the WPC a bit for the next week. That's the championship where I'm actually competitive. I don't know whether I'll be posting puzzles yet for the WPC, but they might show up.
Nine posts also seems the appropriate number for a Sudoku competition. This time they are two practice puzzles for the instructionless round.
If someone has any specific request for a puzzle type, I might be persuaded to make another. Let me know.

I figured this is a round that might need some practice too. I don't think for either puzzle the rules are too hard to figure out. It's possible that both ideas have been done before. I can't remember seeing them before, but my memory isn't perfect. They're not exactly innovative ideas.
I think the first puzzle is probably more like a puzzle in the actual test. It's a just simple addition to a Sudoku grid. I had fun writing them, but with a bit more time I could have made them a bit nicer.
The second puzzle I'm not sure whether it qualifies as a Sudoku puzzle. It has all the rules of a normal Sudoku puzzle but it doesn't uses numbers like most Sudoku puzzles. I think the rules are pretty simple. I had a lot of fun writing them, so they should be fun to solve, I think.
Try the examples too. They're both fun puzzles too.

Rules for Sudoku

In this Sudoku the additional rules are not given. An example and solution are given of the Sudoku variant. Figure out the additional rule from the example and solve the puzzle.

Rules Puzzle #1 (highlight if needed): Each marked 2-cell area contains a 2-digit number, read left to right or top to bottom. The first marked 2-cell area seen by an arrow must contain a larger 2-digit number than the arrow.
Rules Puzzle #2 (highlight if needed): Place 8 arrows (fghimlkj) once in every row, column and marked 3x3 area. Numbers in the grid indicate how many arrows are pointing at that cell.

Puzzle #1

Puzzle #2


Saturday, 7 October 2017

WSC Practice #8: Round 13 - Puzzle 7: Joker Product Sudoku

This is the 8th practice puzzle for the 2017 WSC.

The Joker round is going to be a tricky one. I made an error in the construction of the previous Joker puzzle. Hopefully There are none in these. It's easier to make an error in these puzzles if you just fall back into your standard deductions.
This type actually appears twice in the championship as it also appears in the final team round.
The first puzzle should be a nice solve. I put in a few things that can be done with the Joker in this genre. I'm pretty sure they were easily figured out by yourself, but I think they're nice to see in a puzzle. There's still a few key deductions to find, but it should work well.
The second puzzle is much harder. It relies on a lot of clue interactions, without giving much direct information. It takes a long chain of interactions to place a few digits and consequently figure out the Joker. Even then it's not exactly easy.
I had to check a possible error. I realised I might have forgotten something, but it didn't really influence the puzzle as the deductions still held true. The dumb construction errors really don't allay my fears of making errors in this round by accidentally forgetting a Joker interaction.

Rules for Sudoku

In this Sudoku, numbers on the borders of two cells indicate the product of the digits in those 2 cells. Additionally, there is a Joker digit in the grid. This digit can take on any integer value from 1 to 9 necessary to comply with the rules. It can even take multiple different values within a single cell to satisfy different clues.

Puzzle #1

Puzzle #2

Friday, 6 October 2017

WSC Practice #7: Round 7 - Puzzle 3: Japanese Sums Sudoku

This is the 7th practice puzzle for the 2017 WSC.

I know this round might be a bit contentious to some people. They're afraid it's going to be too puzzly and not enough Sudoku. But just because a Sudoku is named after a puzzle genre, doesn't mean it's completely like that genre. I have a few ways I can imagine these puzzles to be far more like a Sudoku than a puzzle.
I tried to design this Sudoku to not heavily rely on being familiar with Japanese Sums as a puzzle. The logic needed isn't much different than a Killer Sudoku. This is one of the ways I imagined the Sudoku element to shine much more through than the Japanese Sums element of the puzzle. The puzzle shouldn't be too hard if you work the clues in the right order. I hope this helps prepare a bit for the championship.

Rules for Sudoku

In this Sudoku, shade some cells in the grid so that the numbers outside the grid represent the sums of the digits in the white cells in that row or column. The sums are given in the correct order. If there are multiple sums in a row or column, they need to be separated by at least one shaded cell. Some shaded cells may be given.

WSC Practice #6: Round 9 - Puzzle 6: Crossed Sudoku

This is the 6th practice puzzle for the 2017 WSC.

This is not a very new variant. There's been similar variants, one of them being Shaken Clones Sudoku, where digits have to be the same within certain shapes. The only thing different seems to be that the shape is set for this variant. I haven't solved many of these though, so I figured writing one would be good practice for me.
This puzzle is pretty standard. There's not really anything difficult in this puzzle. It just explores the standard things in this genre. If you want a more challenging version of this puzzle, you can remove the 2 in R5C5. The puzzle is still unique that way, but the solving process gets a bit more complicated. You can still get through it logically, but it really isn't that nice. I had made a bad deduction in construction, but it somehow hadn't affected uniqueness. I only found out in the resolve. I decided to add the 2 to just have a smooth solve again.

Rules for Sudoku

In this Sudoku, all crosses contain the exact same 5 digits in any given order. Digits may repeat along a cross.

Thursday, 5 October 2017

WSC Practice #5: Round 6 - Puzzle 9: Big Small Count Sudoku

This is the Fifth practice puzzle for the 2017 WSC.

I wasn't really sure how this variant was going to work. The example has a lot of givens, so I wasn't sure how it would work from that. I set up an opening section and figured I'd go from there. The opening section actually gave more information than I expected and I managed to reduce the second half of the puzzle a bit. It wouldn't get unique though, so I added an extra circle just to fix a small uniqueness issue. It doesn't make for the prettiest Sudoku, but it's a nice result anyway.
I generally like these kind of circle count puzzles, because it gives a fun interaction. Every time a circle gets figure out, a bit of new information gets revealed. It's like you're adding extra clues to the grid during the solving process.

Rules for Sudoku

In this Sudoku there are a number of circles. A digit in a circle indicate either "the number of neighbouring digits bigger than that digit" or "the number of neighbouring digits smaller than that digit" or both. Not all possible circles are marked.

WSC Practice #4: Round 13 - Puzzle 9: Joker Battenburg Sudoku

The fourth practice puzzle for the 2017 WSC.

I feel this round can use all the practice necessary. The Joker rule is something new, as far as I'm aware, and seems to be a bit tricky. Basically the Joker only follows the standard Sudoku rules, but ignores any variant in the puzzle. This is because the Joker digit can assume whatever digit it needs to be for the puzzle to work, even if it means being different digits in the same cell.
The Battenburg Sudoku was one of my own inventions. The reason I picked this type first is because it has both a positive and a negative rule in effect as all possible markings are given. The "All possible markings" rule is a bit odd with the Joker. The way I understand it, in the given solution there are no places where any extra markings HAVE TO be placed. Even if there are markings that could be placed if the Joker assumes the correct parity, they don't have to be placed as the Joker can assume an incorrect parity. I do hope my interpretation is correct, but it seems to conform with the given example in the Instruction Booklet. If it isn't, my apologies for providing an incorrect puzzle. It has happened before. It should still be fun to solve.
I think the puzzle worked out pretty well. The opening should properly show the way this variant interacts with the Joker. Once you've determined the value of the Joker, the solve really takes off. It's probably a harder puzzle because you have to keep reminding yourself of the Joker rule and thread carefully through the puzzle.

[Edit: Puzzle image fixed.]

Rules for Sudoku

In this Sudoku, everywhere a 2x2 square forms a Checkerboard pattern of Odd and Even digits a Battenburg marking is given. All possible Battenburg markings have been given.
Additionally, one digit in the puzzle is a Joker. This Joker digit can be both Odd or Even. The same Joker cell may assume different parities for different 2x2 areas.