Dr. Sudoku Prescribes #143 – Sudoku

Sudoku by Thomas Snyder

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or solve online (using our beta test of Penpa-Edit tools)

Theme: High and Low (Note: This puzzle was one of the qualifying round puzzles from this year’s Arlington Puzzle Festival)

Rules: Standard Sudoku rules.

Answer String: Enter the 2nd column from top to bottom, followed by a comma, followed by the 6th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 2:15, Master = 3:15, Expert = 6:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Dr. Sudoku Prescribes #142 – Sudoku

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Four-leaf Clover (Note: This puzzle was one of the qualifying round puzzles from this year’s Arlington Puzzle Festival)

Rules: Standard Sudoku rules.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 3:00, Master = 5:15, Expert = 10:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Dr. Sudoku Prescribes #141 – Sudoku

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Logical (Note: This puzzle was one of the qualifying round puzzles from this year’s Arlington Puzzle Festival)

Rules: Standard Sudoku rules.

Answer String: Enter the 4th row from left to right, followed by a comma, followed by the 6th row from left to right.

Time Standards (highlight to view): Grandmaster = 2:00, Master = 2:45, Expert = 5:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

The Puzzle Robot #16 – Surprise Sudoku

Sudoku by Serkan Yürekli

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or solve online (using our beta test of Penpa-Edit tools)

Theme: Surprise Sudoku

Rules: Standard Sudoku rules. Also, there is a mystery rule that must be determined by looking at the example at the top of the puzzle.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 6:15, Master = 8:30, Expert = 17:00

Solution: PDF

Editorial Note: While this is an original sudoku for GM Puzzles, this particular “surprise” gimmick from Serkan first appeared on the SudokuCup 10 test with a different puzzle.

Dr. Sudoku Prescribes #132 – Sudoku

Sudoku by Thomas Snyder

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or solve online (using our beta test of Penpa-Edit tools)

Theme: Two Rings

Rules: Standard Sudoku rules.

Answer String: Enter the 5th row from left to right, followed by a comma, followed by the 5th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:15, Expert = 4:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Dr. Sudoku Prescribes #129 – Sudoku

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Even/Odd Clover

Rules: Standard Sudoku rules.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 3:00, Master = 4:45, Expert = 9:30

Solution: PDF

Note: This puzzle is probably harder than a typical Monday, but was the style we always had in mind for 9/9, which the World Puzzle Federation recently set as “International Sudoku Day”. Happy solving! Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Dr. Sudoku Prescribes #126 – Sudoku

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: A Series of Falls — all 5 digits runs from 1-5 to 5-9 appear. (This puzzle also appeared on the recent Indian Sudoku Championship.)

Rules: Standard Sudoku rules.

Answer String: Enter the 4th column from top to bottom, followed by a comma, followed by the 8th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 1:40, Master = 2:20, Expert = 4:40

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Detuned Broadcast #5: Sudoku

Sudoku by Tom Collyer

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Two by Three by Four

Rules: Standard Sudoku rules.

Answer String: Enter the 1st column from top to bottom, followed by a comma, followed by the 9th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 3:15, Master = 4:30, Expert = 9:00

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

Championship Chatter – Final Puzzles and Thoughts

Here are the final puzzles from the US Sudoku Qualifying Test that I wrote. Both are less common types. Tomorrow will finally bring some new puzzles, and I hope some surprises too.

The first of this set, a “Seek-and-Spell” variant, is a style that took on a life of its own on this website a few months ago as more and more constructors kept submitting it. I wanted a very United States sort of puzzle somewhere on this test and found a good letter set to get 5 states into this grid. I wanted OHIO from the start as an easy Seek-and-Spell rule placement. But the value of states like MONTANA and INDIANA became clear during construction. This may have been the only case on the test where some non-sudoku logic puzzling skill would really accelerate the solve as the Seek-and-Spell placements are quite limited and getting them fixed makes the rest much easier.

The second of this set is a style I first created for a Czech/US Sudoku Championship several years ago and one that I keep bringing out every year typically for championship season. It is one of the easier styles construction-wise to get started with creative themes as it does not take a lot of digits in either grid before the linked cells really start to force the solve. But occasionally getting both grids to behave by the end can be hard. Here, my seeds were two different styles of basic step in the two grids. And after finding the linked regions, consistently ping-ponging between the two puzzles to get to the end. It is another of my favorites on this test.

Not posted this week were the great submissions from Wei-Hwa Huang. This year I gave him a sketch of the styles I wanted and he delivered in a large way. For example, I had a basic concept to play with Binary in a 6×6 grid with missing digits much like the Indian GP test had a play on this with Braille. Wei-Hwa took it farther than I did though with 0-7 and three bits being a perfect choice and his example and test puzzle were both quite fun. The Property Sudoku also had quite an elegant solve and his Diagonal had a good, but fair, challenge.

Sudoku by Thomas Snyder

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or solve online (using our beta test of Penpa-Edit tools)

Theme: United States

Rules: Standard Sudoku rules except that instead of the numbers 1-9 this puzzle uses the letters ADEHIMNOT. Also, clues in the grid represent typical “Seek and Spell/Kanaore” clues; specifically, it must be possible to read each of the words/phrases listed below the grid by starting at the indicated number, moving one cell in the direction indicated by the arrow, and then continuing to move one cell at a time up, down, left, or right to complete the word/phrase. No cell may be used more than once in a single path, but the same cell can appear in the paths of different words/phrases.

Answer String: For the USSQT, the answer strings were a set of rows/columns encountered late in the puzzle. For this week, you can just hit the solved button on an honor system if you think you’ve solved it.

Solution: PDF

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Logical

Rules: Standard Sudoku rules for each of the two grids. There are three shaded regions in each grid. The shaded regions must exactly match between the puzzles, but which shaded regions correspond to which must be discovered.

Answer String: For the USSQT, the answer strings were a set of rows/columns encountered late in the puzzle. For this week, you can just hit the solved button on an honor system if you think you’ve solved it.

Solution: PDF

Championship Chatter – Simply Classic

The Sudoku Grand Prix (GP) has certainly now shown a variety of test styles after the creative but unorthodox Turkish test this past weekend. I’m still not sure exactly what the GP is trying to be, and I have no idea what the “playoff” in Beijing will look like (does anyone know anything about the rules or puzzle designers?), but the list of 10 competitors to qualify is getting much clearer now. Quite incredible to have a different winner for each event so far.

Our test, like some others in the GP such as the UK test, had a pretty clear goal to have a lot of elegantly constructed sudoku in pretty simple styles to test basic sudoku skills. All our puzzles had fair, logical solution paths, and we expected many solvers would finish. And as I still think of this as a US Sudoku Qualifier first, and a GP contest piece second, I was glad we got two of the qualifying Americans to submit all of the answers even if one had a mistake. While this is now quite belated, congrats to Jason Zuffranieri for his US victory and to Bastien Vial-Jaime for the overall victory.

Here is the second pair of classic sudoku that appeared on that contest.

Sudoku by Thomas Snyder

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or solve online (using our beta test of Penpa-Edit tools)

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools)

Themes: Both geometric and logical

Rules: Standard Sudoku rules.

Answer String: For the USSQT, the answer strings were a set of rows/columns encountered late in the puzzle. For this week, you can just hit the solved button on an honor system if you think you’ve solved it.

Design Notes (highlight to view): The third classic sudoku (and first here) was built around an even versus odd theme and recognizing this unusual partitioning of the digits will be key to making fast progress. A bunch of singles (either naked or hidden) can be found based on parity around the middle sections which finally breaks through to the final solution. The fourth classic sudoku (and second here) was constructed to have an early and pretty clear single sticking point aspect to it. The geometry suggests something should be present in the almost full rows or columns. If solvers focus on those most constrained positions in the first column, they will find a naked pair [89] that gets the whole solve going. While none of these classic puzzles required extremely difficult techniques, keeping the solving paths somewhat tight at the very start makes them good competition challenges in my mind.

Solutions: PDF and PDF