Sunday, 29 November 2015

Daily League #49: Descriptive Pairs or Next To Nine Sudoku

This is the fifth puzzle in my 'A or B Sudoku' series. It is a combination of Descriptive Pairs Sudoku and Next To Nine Sudoku. I thought I might be able to combine these genres as they both use two digits for clues.
These are two types that suit my design style a bit more, because I like designing Sudokus without any givens in the grid. It was a bit hard to find a good opening, so I went for a relatively obvious opening clue. The opening is pretty narrow and it takes a while for the solve to open up a bit. I'm pretty happy how it turned out. I thought the two types work well together.

Rules for Sudoku

In this Sudoku each pair of digits is either a Descriptive Pairs Sudoku clue or a Next To Nine Sudoku clue. In a Descriptive Pairs Sudoku clue, one of the digits indicates the position of the other digit in that row or column when looking from that side. A Next To Nine Sudoku clue indicates the two digits that border the 9 in that row or column. Different clues can conform to different rules.

Click to enlarge

Sunday, 22 November 2015

Daily League #48: Edge Sums or Frame Sudoku

This is the fourth puzzle in my 'A or B Sudoku' series. It's a combination between Edge Sums and Frame Sudoku.

These two type are pretty similar. One uses the sum of the first two cells and the other the sum of the first three cells. I find both types fun to solve, but I do think they get the same pretty fast. There's a few variations on them that make them a bit more interesting, like Hi-Lo Frame Sudoku and Frameless Sudoku. I thought the combination of the two and three cell sums might make it more interesting. I am happy with how the puzzle turned out, especially getting the ending to work with so few clues was fun to figure out. Hope you enjoy it too.

Rules for Sudoku

In this Sudoku the numbers on the outside indicate the sum of the digits in the first two or first three cells seen in that row or column from that direction. The number of digits can differ between different sums.

Click to enlarge

Saturday, 21 November 2015

Puzzle #169: Fortress Sudoku

For his last two puzzles for the Daily League, Tom Collyer has been playing around with the same layout in his Extra Region and Clone Sudoku and his Very Odd Sudoku. This second puzzle can be solved under a second rule. After having solved it both ways, I tried solving it under a few other rules that might be presented that way. None of them worked. But I found that solving it under Fortress Sudoku rules lead to some interesting deductions by removing a few of the givens. So with that opening, I started playing around a bit what givens would make it unique. This is the result. I think it turned out nicely.

Rules of Sudoku

In this Sudoku digits in grey cells are larger than all orthogonally adjacent white cells.


Click to enlarge

Sunday, 15 November 2015

Daily League #47: Palindrome Or Rising Sudoku

Here is the third puzzle in my 'A or B Sudoku' series. This time it is a combination between Palindrome Sudoku and Rising Sudoku. Rising Sudoku might be a bit unfamiliar. It's basically a Thermometer Sudoku without a bulb to indicate the low point of the line. I saw them more often years ago, but I think now Thermometer Sudoku has become a bit more the go-to genre.
I wasn't sure if this combination would work very well. It was a bit hard to figure out how to get a start in this Sudoku, without giving away too many givens. The construction was a bit troublesome as I ran into situations without a solution far too often. The problem was that a lot of areas wouldn't resolve themselves early in the solve and by the time they did, there would be a contradiction with clues I had laid out in the meantime. In the end, I think the puzzle worked out nicely.

Rules of Sudoku

In this Sudoku a grey line is either a Palindrome Sudoku or a Rising Sudoku clue. In a Palindrome Sudoku clue the digits along the grey line form a Palindromic sequence; the sequence can be read the same from either end. In a Rising Sudoku clue, the digits form a rising sequence from one end to the other. This sequence does not have to be an arithmetic sequence. Different grey lines can conform to different rules.


Click to enlarge

Sunday, 8 November 2015

Daily League #46: All Odd Or All Even Sudoku

This is the second puzzle in my 'A or B Sudoku' series. This time it's a combination of Odd and Even Sudoku.

This combination has been done before, but I've always enjoyed solving them. I generally like puzzles with parity. I used the same layout for this puzzle as one of my earlier puzzles, namely my Renban Sudoku (and in a sense my Arrow Sudoku). I thought this layout would work well for this genre and I was right. I found some interesting interactions in this layout. These interactions might lead to some harder logic, but they should be fun to figure out.

Rules for Sudoku

In this Sudoku grey cells within a single marked 3 by 3 area are either all odd or all even. This can differ between different areas.


Click to enlarge

Sunday, 1 November 2015

Daily League #45: Clone Or Extra Region Sudoku

After a Daily League hiatus of over a year, I've written a number of Sudokus again. I'm planning on keeping it up for a while.

For this month, all my Sudokus will fall in a particular theme. This theme is "A or B Sudoku". This means that clues for two different genres appear in the Sudoku and it's up to you to figure out which clues are part of which genre. The reason for this theme is that one of my favourite Sudokus I have written for the Daily League was my Ace Sudoku. I really enjoyed writing that puzzle, playing around with getting the different rules having to be used in different areas. I think it's a fun solve personally. So I started playing around with different rules that are normally presented in the same way. When I had a few out, I decided I would be posting them in the Daily League.
The first puzzle is a combination of Clone and Extra Region. I first searched for a nice layout that allowed for multiple 9 cell areas that don't touch each other. The three I-shaped regions look nice and work well together. I think the combination worked out well, but can probably be improved on a bit.

Rules for Sudoku

In this Sudoku each grey area is either an Extra Region Sudoku or a Clone Sudoku clue. A Extra Region Sudoku clue contains the digits 1~9 exactly once. A Clone Sudoku clue has the exact same digits in the same place as one or more of the other grey areas, without rotation or reflection. Different grey areas can obey different rules.


Click to enlarge