Friday 29 April 2016

16th 24-Hour Puzzle Championship

The 16th 24-Hour Puzzle Championship was held in Budapest this weekend. As always the championship featured 14 puzzle sets to be solved over 24 hours, with each round lasting 100 minutes, with only 10 or 20 minute breaks in between. Neil Zussman was this year's winner with a slim 10 point lead over Robert Vollmert in second place and a 23 point lead over Michael Mosshammer in third place. Full results can be found here.

All puzzles of this championship (except round 11) can be found here. If you need an example of any of the puzzles, you can find the instruction booklets here.

I provided a set again this year. It was the 8th set to be solved between 11pm and 12:40am. The set contained 24 puzzles. It featured 12 genres, with one puzzle being a standard and one puzzle being a variant. I was originally going to include only 6 genres and two standard puzzles and two variants. I found it hard to decide on the genres to provide enough variation. I tried to keep all variations different per genre, to add to the variation in the round. I think it ended up being a good mix.
Robert Vollmert was the top scorer of the round with 810 points.

Puzzles can be found below

Sunday 24 April 2016

Daily League #66: Round Off Sudoku

This is the last puzzle that was originally written for the Polish Sudoku Championships.

The last puzzle is a Round Off Sudoku. I've solved a number of them, but had never written them. Most of these puzzles were written by Richard. I wanted to give a nice pattern with relatively few cages. I thought the problem would be getting it unique, but at the start I ran into a lot of situations where there was no solution left. When I finally figured out where I was messing it up, it was still a struggle to get it right. I had a few puzzles that turned out a bit too hard, where I didn't think it would fit into a puzzle competition. The opening created a few sticking points I had to avoid, which would easily lead to uniqueness issues that I had no way to fix. This was the puzzle that came out in the end. It shouldn't be too hard. Enjoy.

Rules for Sudoku

In this Sudoku, the grid has a number of marked two cell dotted cages. The two digits in these cages form a two digit number read from left to right. The number in these cages indicates this number rounded off to the nearest multiple of 10. Numbers ending to 1-4 are rounded down, numbers ending in 5-9 are rounded up.

Click to enlarge

Tuesday 19 April 2016

Polish Puzzle Championship 2016

Last weekend were the Polish Sudoku and Puzzle Championships. Jan Mrozowski won the Sudoku event and Przemysław Dębiak won the Puzzle event. You can find all the puzzles in the following links: Sudoku and Puzzle. My puzzles are round 2.

I provided one of the rounds for the puzzle championships. I've kept the same structure that I've used for the last two year with a smaller, easier and a larger harder puzzle of each type. I think it works well for these championships. I've been trying to run through different genres each year. So this year I again used nine different genres. I think it resulted in a good mix of different types.

Puzzles can be found below.

Sunday 17 April 2016

Daily League #65: Rossini Sudoku

This is the third puzzle that was originally written for the Polish Sudoku Championships.

This week it's a Rossini Sudoku. I was trying to design a puzzle without any givens. But I noticed pretty quickly on that this wasn't as easy as I had hoped. The middle of the grid is a lot less accessible as I had thought in advance. I remember seeing one before without givens, but to achieve that I'll need to set up the middle boxes better than I did now. But as I liked how the opening worked out, I finished the puzzle with a few givens. I am happy how it turned out. Enjoy.

Rules for Sudoku

In this Sudoku arrows on the outside indicate that the first three digits in that row or column, when looking from that side, are in ascending order in the direction of the arrow. All possible arrows are given, so if there's no arrow the digits can't be in ascending order.

Click to enlarge

Sunday 10 April 2016

Daily League #64: Hi-Lo Frame Sudoku

This is the second puzzle that was originally written for the Polish Sudoku Championships.

This week it's a Hi-Lo Frame Sudoku. I like the Hi-Lo concept as it gives a little bit of extra information about the third digit that isn't involved in the sum. I've written a few before, but I haven't used it for the league before. I did combine it with another variant, but it should be fun by itself. I think this is probably the hardest puzzle in the set because it requires finding the right few steps through the opening. I prefer not given all possible clues as otherwise you get a big opening on where either the 1 or 9 goes within a box. In the end the path gets a bit more flexible as you have placed digits to help out. Enjoy.

Rules for Sudoku

In this Sudoku the numbers on the outside indicate the sum of the highest and lowest digit in the first three cells in that row or column when looking from that side.

Click to enlarge

Sunday 3 April 2016

Daily League #63: Clone Sudoku

This month there were four puzzles I wrote for the Polish Sudoku Championships. They weren't needed though. As I hadn't used any of these types for the League, I figured I could use them for that. I wrote these puzzles to fit more in a competition and I expect them to be a bit easier than normal. I can never be 100% sure as I sometimes assume an opening deduction is pretty straightforward, but that doesn't mean it can't be hard to find. I'd love to hear some feedback on whether these puzzles would be suitable for a championship. I haven't written many Sudokus for competition solving.

The first puzzle is a Clone Sudoku. I thought the pattern of givens around the Clone region looked nice. I was hoping to make the pattern work with two empty boxes, but I couldn't get it unique. One extra clue did make it unique. It makes the puzzle asymmetric, but it is still a good solve.

Rules for Sudoku

In this Sudoku, digits in the same place in both grey figures must be identical.

Click to enlarge