Ask Dr. Sudoku – Championship Chatter

Last Saturday finished another 6 week cycle of offerings from Grandmaster Puzzles. It also finished a rather busy 6 weeks of puzzle construction and testing, including three different puzzle championship rounds. Two of these have now been hosted (the US Sudoku Qualifying Test/Grand Prix Contest, and the US Puzzle Championship) and one will be a future surprise. This gives me reason to think a pause for some reflection and discussion about some of these puzzles would be a valuable use of the “gap” time before our next spurt of new puzzles and possibly new genres begins. [It also gives me a chance to hopefully address some server issues.]

The USPC is one of the few championships that follows the World Puzzle Federation’s model of puzzle balance including observational puzzles, word manipulation puzzles, and often some “trick” puzzles alongside a mix of classic constraint satisfaction types and variants. I figured — given existing contributors — that I would be most called upon to make some innovative word and observational puzzles alongside some original (read: previously unseen) variants that would hold new surprises for all solvers. The first puzzle I wanted to highlight is one that is meant to be recognizable and friendly to even the casual solver: the USPC Word Search.

I had a few ideas in mind this year for creating an interesting word search, and settled on a variety rebus gimmick where entries may or may not contain a shortened set of characters in a single square. Having previously used digit word phrases for a Sudoku Masterpieces puzzle (Some Err1ous Spelling!) and having much of that research on hand, I took my time getting a good interlinked set of “Digi2rds” together for the USPC puzzle. The missing middle shaped like an octothorpe was another goal I had in mind to give the puzzle some character. I also laid some traps around the middle for solvers trying to intuit words too soon. While many solvers will turn their noses up at a word search, I still see great value in having such puzzle styles represented on a puzzle championship. I hope I managed to give an intriguing challenge with the puzzle below.

Word Search by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab mode to shift between line drawing, letter/number entry, and shading modes)

Theme: Hidden Numbers

Rules: Standard Word Search rules. Also, a digit may be used in place of its letters when spelled out. For example, “DIGIT WORD SEARCH” might appear in the grid as “DIGI2RDSEARCH”. 25 characters are missing from the grid and must be identified to complete the puzzle.

Answer String: For the USPC, the answer string was the 25 missing characters in order. For this week, you can just hit the solved button on an honor system if you think you’ve solved it.

Solution: PDF

Sunday Surprise #6 – US Championship

I had not intended to have a repeat author for a Sunday Surprise so soon, but Craig Kasper sent along a really nice surprise sudoku to mark the US National Championship we’ve been focusing our attention on all weekend. See if you can find your way through to the very end.

Surprise Puzzle by Craig Kasper

PDF

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

Theme: That US national championship happening this weekend; speaking of which, congratulations to the top finishers at the US Puzzle Championship, whomever you turn out to be.

Rules: Standard Sudoku rules. Also, the regions are irregularly shaped; instead of numbers, use the letters in “I’D GOLF, MAN” once in each row, column, and region.

Answer String: Enter the letters in the third column, from top to bottom, followed by the letters in the seventh column, from top to bottom. USE CAPITAL LETTERS.

Solution: PDF

Dr. Sudoku Prescribes #112 – TomTom

TomTom by Thomas Snyder

PDF

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

Theme: Triple Play

Rules: Standard TomTom rules, using digits from 1-9.

Answer String: Enter the 4th column from top to bottom, followed by a comma, followed by the 6th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 12:30, Master = 25:00, Expert = 50:00

Solution: PDF

Note: Follow this link for other classic TomTom. If you are new to this puzzle type, here are our easiest TomTom to get started on.

Dr. Sudoku Prescribes #111 – Shape Sudoku

Sudoku by Thomas Snyder

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Sudoku number entry mode and a shading mode to manage the shape inventory.)

This is a “Franken-Friday” puzzle variation.

Theme: Plus Signs

Rules: Standard Shape Sudoku rules.

Answer String: Enter the 9th row from left to right, followed by a comma, followed by the 4th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 7:00, Master = 15:00, Expert = 30:00

Solution: PDF

From the Foxger’s Den #31: Tapa

Tapa by Grant Fikes

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)

Theme: Logical

Rules: Standard Tapa rules.

Answer String: Enter the length in cells of each of the shaded segments from left to right for the marked rows, starting at the top. Separate each row’s entry from the next with a comma.

Time Standards (highlight to view): Grandmaster = 1:15, Master = 2:30, Expert = 5:00

Solution: PDF

From the Foxger’s Den #30: Fillomino

Fillomino by Grant Fikes

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a number entry mode.)

Theme: 28 “dice”, opus #2 (See here for the first in Grant’s 28-given series of Fillominoes.)

Rules: Standard Fillomino rules.

Answer String: For each cell in the marked rows/columns, enter the area of the polyomino it belongs to. Start with the 5th row, followed by a comma, followed by the 9th row.

Time Standards (highlight to view): Grandmaster = 2:20, Master = 3:30, Expert = 7:00

Solution: PDF

Note: Follow this link for other classic Fillomino and this link for more variations on Fillomino puzzles. If you are new to this puzzle type, here are our easiest Fillomino puzzles to get started on.

From the Foxger’s Den #29: Battlestar

Battlestar by Grant Fikes

PDF

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

This is a “Twisted Tuesday” puzzle variation.

Theme: None

Rules: Variation of Star Battle. There are still two stars per row and column, but instead of regions there is an irregular grid. Stars cannot be placed in adjacent cells that share an edge or corner.

Answer String: For each row from top to bottom, enter the number of the first column from the left where a star appears (gray numbers at the top of the puzzle here are given to help). Enter these numbers as a single string with no separators.

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:30, Expert = 5:00

Solution: PDF

From the Foxger’s Den #28: Slitherlink

Slitherlink by Grant Fikes

PDF

or solve online (using our beta test of Penpa-Edit tools in edgex mode where left click+drag draws lines and right click marks X’s)

Theme: Deja Vu?

Rules: Standard Slitherlink rules.

Answer String: Enter the length in cells of each of the internal loop segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 1:10, Master = 1:30, Expert = 3:00

Solution: PDF

From the Foxger’s Den #27: Masyu

Masyu by Grant Fikes

Click here for larger image

PDF

or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s)

Theme: Logical theme encountered during the solve

Rules: Standard Masyu rules.

Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 8:45, Master = 11:00, Expert = 22:00

Editorial Note: This is our first Giant puzzle from Grant. Not because he hasn’t been writing many; we’ve been keeping most of his giants for The Art of Puzzles so consider this a teaser for some of the great puzzles that will be in that collection.

Solution: PDF

Dr. Sudoku Prescribes #110 – Skyscrapers (Even/Odd)

Skyscrapers by Thomas Snyder

PDF

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

This is a “Franken-Friday” puzzle variation.

Theme: No givens (this variation was inspired in part by the Even/Odd round at the 19th WPC by Lukasz Bozykowski.)

Rules: Standard Skyscrapers rules. All even digits (and only even digits) have been shaded gray. Note: this means that all unshaded digits, including unshaded outside digits, are odd.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 3rd row from left to right.

Time Standards (highlight to view): Grandmaster = 2:45, Master = 4:00, Expert = 8:00

Solution: PDF