David Badger’s 1001 Hard Sudoki


David Badger, a prolific composer of giant grid Sudoku puzzles, now has a giant book of 1001 standard size puzzles, self rated as “hard”. The publication date, listed in the back,  is June 17, 2017. Here is the standard Sysudoku review of this collection, pre-selecting puzzles 1 to 1001  in steps of 100.

David does many things a little differently, besides grid sizes of 12 x 12, 16 x 16, and 25 x 25 cells and box sizes of 3 x 4, 4 x 4 and 5 x 5.  Instead of extending fill symbols by alphabet, such as the hexadecimal number system {1, 2, …, E,F}, David uses two digit decimal numbers as filling symbols. That must make pencil marking a challenge. His 1001 Hard book carries no copyright notice. Like many of today’s collection books, there is no text of any kind.  Pages are large enough for four grids, with answers at the bottom of each page. The puzzles themselves are formatted in the customary way.

For an overview of the Sysudoku difficulty level, here is the review table:

Two reached advanced, one bypass victim, one box marking victim, and eight collapsing in line marking.  Anything can happen. 

I did 11 pre-selections because puzzle 1001 had a full page rendering, which I took as possibly significant. Turns out, it wasn’t. On 701, the bypass victory depended upon a two 3-fills, and finishes with another.

Here is the grid where the trace ends. Mop up is freestyle.

 

 

 

 

 

 

 

 

 

The advanced track of David’s 301 wasn’t typical .  You might like to examine these three potential UR’s, Dr. Holmes, and ferret out why they fail to eliminate any suspects

From there, investigate the XY railway of his beast, and find an ANL and extension ANL that eliminate a bunch of 7’s.

 

 

 

The extra bv will expand the railway into a  serpentine maize, to which you are to apply Medusa coloring, for a glorious finish.

I’ll checkpoint you on this next time, along with a play-by-play of 101, shown here. You can check me out on the above 101review table report, and find its advanced goodies.

 

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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