Saturday, 27 July 2013

Daily League Sudoku #22: Diagonal Sudoku

This week again something standard and easy. I don't often write classic Sudokus or standard variants. I think it is because I can't really put anything that creative in my designs for them. I can make them visually pleasing, but that is generally it. I like to put interesting logic in my puzzles, but I have trouble achieving that with normal Sudoku. That's probably because there's too many of them out there, that I feel I can't really offer anything new to the mix. Even when I try I tend to have to give up on it, because otherwise I can't get it unique. I think this one worked out okay though. I expect very fast times though from the best solvers. I don't think there are really many stumbling blocks.

Recap of the last Daily League week:

Saturday: Classic Sudoku by Tom Collyer
Sunday: Edge Product Sudoku by Seungjae Kwak
Monday: Just One Cell Samurai Sudoku by Tiit Vunk
Tuesday: Repeated Neighbours Sudoku by Prasanna Seshadri
Wednesday: Outside or Skyscraper Sudoku by Bastien Vial-Jaime
Thursday: Twin Detector Sudoku by Sina Hera
Friday: Even Sudoku by Tom Collyer

Daily League PDFs:
Week 25
Week 26
Week 27

Rules for Sudoku

In this Sudoku you also have to put the digits 1~9 once on the marked diagonals.

Friday, 19 July 2013

Daily League Sudoku #21: Hi-Lo Inner Frame Sudoku

I'm back with a Daily League Sudoku this week. I'm posting the Friday puzzle as Tom needed a bit more time and my puzzle is ready. This week I've written a combination of two nice types. The Inner Frame I first saw on the 2012 US Sudoku Qualifiers. The Hi-Lo Frame Sudoku I first encountered on the 2011 Dutch Sudoku championships.
I think they work well together. The Inner Frame idea leaves you to use some combinations that would otherwise not be possible, because there is more room for repeated digits within the different sums. I chose for an easier layout of clues that all overlap, which I think makes the solve a bit more friendly. I think it worked out well. I hope you enjoy it too.

Daily League PDFs:
Week 20
Week 21
Week 22
Week 23

As a final note, all puzzles are also solvable each day on SudokuCup. The puzzles appear a day later than in the group.

Rules for Sudoku

In this Sudoku, the numbers on the outside indicate the sum of the highest and the lowest of the three digits in the 2nd, 3rd and 4th cell seen from that side.

Saturday, 13 July 2013

Puzzle #162: Pentopia

I should be in Australia by now, getting used to driving on the left, kangaroos and koalas, still not liking meat pies and trying to understand what cold means in Australia. This post is written 6 days ago though, so I might be completely wrong.

These two puzzles I have also written earlier. Checking the number of tags on my blog, it's no surprise that I would have chosen to write Yajilin and Pentopia puzzles. They're just types that come very easy to me and I always find fun to write and hope people actually like to solve. But they generally seem well received. Pentopia featured on the USPC this year, after also featuring on the WPC last year. They've also been published in Breinbrekers. So I guess that means it is getting more exposure than just my blog.
The puzzles are pretty good. The first one is a 10 clue puzzle that has a fun opening, but I couldn't get it unique with that 10th clue in a symmetrical position, so I moved one of the clues to acchieve a unique puzzle. The second puzzle has an easy opening, but takes a bit more finesse to finish.

Rules for Pentopia

Puzzle #1

Puzzle #2

Wednesday, 10 July 2013

Puzzle #161: Yajilin

At the point of this post I'll probably be somewhere above Asia. I'm too lazy to properly work out where my plane should be. I'm flying to Australia today. Hopefully there will be no problems and I'll get through customs there without any problems. Watching those border control shows really makes it look a bit scary. But I'm smart enough to not stock half my suitcase with food, so that should be okay, right?

The puzzles I'm posting today I made a while back, but never ended up being used where I made them for. As I now know they won't be in there, I can safely post them here. I think they worked out well. The first one was intended to symmetrical too, except I couldn't make it unique with the opening I had used. But then I noticed I could make it unique if I were to remove one of the clue squares. I think it worked out well. The second one uses some logic I don't often manage to put in these smaller Yajilin puzzles. I'm not sure if it will get noticed though. I think it works out nicely and is very reminiscent of my other Yajilins.

Rules for Yajilin

Puzzle 1

Puzzle 2

Sunday, 7 July 2013

Daily League Sudoku #20: Max Difference Sudoku and Ace Sudoku

I've been a bit busier lately and didn't find the time to write out my blog posts. So I'm using this to post the two Sudokus I had posted in the Daily League page in the last 2 weeks. They were both new ideas as far as I'm aware of, but both used familiar ideas, just used in a way not done before. I think I more often go for new ideas because I don't think I can add more to common Sudoku genres as there are already so many available online.

The first puzzle iss Max Difference Sudoku. It is a variant where the maximum difference between 2 adjacent digits are marked for some rows and columns. I liked the interactions as both high and low digits can be used to force placements if you use the clues appropriately. This is actually the second puzzle as I had made a bad deduction during construction, which made the whole puzzle fall apart. I think this one actually worked out better than the way first one should have worked.

The second puzzle is an Ace Sudoku. It's a tricky variant where each 3x3 region obeys one of two rules that have been used in other puzzle, namely that either adjacent digits can't have a difference of 1 or that adjacent digits can't sum to 11. You have to deduce which of these two rules applies for each region. I always like these choice puzzles. The most common way this has been used is All Odd Or All Even Sudoku. The construction for this one took a while. I had the opening set up pretty quickly, but then spend ages trying to figure out if I could place the remaining digits in this pattern, so that it was unique. Many tries ended up without a solution as some 3x3 regions wouldn't obey either of the rules and a few ended up with multiple solution. But after a while I managed to find this puzzle. It has a few tricky steps in the middle, where you need to find the critical steps to make progress. I like how it turned out though and think it really nicely uses the rules of the genre. The name of the puzzle is derived from the Ace in Blackjack.

Rules for Sudoku

Max Difference Sudoku

In this Sudoku numbers on the outside indicate the maximum difference between two adjacent digits in that row or column. The indicated difference has to appear at least once in that row or column.

Ace Sudoku

In this Sudoku within every 3x3 region neighbouring digits either don't have a difference of 1 or don't have a sum of 11. One of these rules is true for each 3x3 region, but the other one doesn't necessary have to be false. Which of these rules is true can differ between different 3x3 regions. There are no restrictions between adjacent digits in different 3x3 regions.