Saturday, 8 July 2017

2017 Sudoku GP: Round 7 Russia

So this was a round that I really wanted to finish to cement a good end to the GP series.  the puzzles this time round were provided by Andrey Bogdanov of Russia, a stalwart puzzle writer who also writes some interesting, if rather difficult sudoku variations as well.

Enjoyment: 6/10
Classics: 6/10
Favourite Puzzle: Killer Sudoku

The theme for this round was Tetrominoes, of which there are 5: L, I, T, S and O.

1-5 Classic Sudoku (12, 13, 19, 21, 28 points)
Nice enough classics, although the first two cannot possibly be scored consistently with the classics in the rest of the competition.  I am inclined to believe that the test probably had one too many puzzles.  I only got around to two of these during time, with a silly mistake in the 13 point puzzle.

6 Letter Sudoku (47 points)
Just a classic, but using the letters TOMSLINER.  The unfamiliarity with the symbols always makes these a little slower, but I think this was genuinely quite a hard classic.  I would have preferred to have had this as a 1-9 classic and then swapped in one of the previous classics to have as the Letter puzzle.  On the other hand the letters did have a tetromino theme.  It feels like givens at R6C6 and R6C7 were omitted in error given the otherwise symmetrical positioning of the givens.

7 Nonconsecutive Sudoku (71 points)
This was hard, and I had to guess a lot.  On the other hand, you could solve this very quickly with a punt if you noticed that in all 9 rows and columns you had sets of repeating triplets.  It's definitely worth noting that repeating triplets is definitely a theme within all non-consecutive puzzles, however this punt on both rows and columns is far from guaranteed - there was a filthily difficult non-consecutive sudoku puzzle in the 24h Puzzle Championship earlier in 2017 which did not conform to this pleasing regularity.  Givens as tetrominoes.

8 Cloned Shapes Sudoku (29 points)
Or Clone Sudoku as it is better known as.  I didn't have time for this during the test.  The tetromino theme continued as the cloned areas.

9 No Touch Sudoku (76 points)
I thought this was over-valued.  Sure it was difficult, but there were 50 point puzzles on this puzzle that both felt harder and took longer to solve.  Maybe I'm just reasonably good at this type.

10 Odd Sudoku (18 points)
Pleasant enough.  More shaded tetromino areas.

11 Renban Sudoku (28 points)
Again, I prefer Renban Groups Sudoku.  Again, pleasant enough.  Again, shaded tetromino areas.  Also worth noting I got the answer keys out having solved only 2/3 of the puzzle.

12 Antiknight Sudoku (64 points)
Well, this is at least better than Antikinght Sudoku from Round 6, but a hyphen would be nice.  Not a type I'm good at, and combined with this not being particularly easy probably meant I really suffered on the points per minute ratio for this puzzle.  Givens as tetrominoes here.

13 Killer Sudoku (48 points)
The recent trend for Killers with a reduced number of cages continues - in this case the cages were all of size 4.  This was a nice puzzle, probably my favourite of the set, but definitely undervalued.

14 Placement Sudoku (55 points)
More of a puzzle-y type, albeit not particularly difficult.  GM Puzzles refers to these as Shape Sudoku.  My solve was a bit dopey and probably took twice as long as it needed to.  You'll never guess what the shapes to be placed in the grid ended up being...

15 Figure Sum Sudoku
Again a puzzle-y type to fit the tetromino theme.  I think this probably crosses the line over what I'd like to see included in the Sudoku GP.  I didn't solve this in time as after making a start I couldn't see further logic.  After time, I went into a more puzzle solving mode, went with a configuration which seemed likely and had solved the puzzle 3 minutes later.

So, I'd left 5 puzzles with 1 mistake - not anywhere near finishing (albeit that 4 of the remaining puzzles, as well as the mistake were low points) which is a bit disappointing, but I don't think I was completely on top solving form.  I think the results tend to show that there was probably one too many puzzles here, even if the top solvers were around the 1 hour 5 mark again, which is at least vaguely consistent with most of the other rounds in this series.

Top 3:
1. Tiit Vunk (859.7 points)
2. Prasanna Seshadri - a.k.a our esteemed and remunerated WPF director (834.3)
3. Jan Mrozowski (811.2)
As for the Brits - a little disappointing:
56. Tom Collyer (426)
69. Mark Goodliffe (397)
71. Heather Golding (390)
For the overall, Mark sits on 2658 and Heather is on 2588 from their best 6.  I have only had 5 scoring rounds, hitting 2289, which means I need at least 300 to catch Heather and 370 to catch Mark (not taking into account any improvements they make on their worst score) for Round 8 - which I'd expect to do based on my scores so far.

Adding 600 to my score takes me to 44th place, and with 40th currently 696 points ahead, that top 40 placing is very much looking like an outside bet - this would require finishing the set with at least 10 minutes to spare, which is in all likelihood a top 10-20 performance.  Let's see how it goes!


  1. About puzzle 15, what do you mean when you say "went with a configuration which seemed likely"? Based on my solve(after the contest), the puzzle was not so much about finding out the configurations (or how a tetromino could be placed in whole)as it was about finding out which cells (are/are not) to be shaded or are part of tetrominoes which helps to progress further.

  2. Yes, you are right (whoever you are!) - I didn't go blindly placing entire tetrominoes but was rather guided by which cells seemed likely to be shaded.

    I think in reality if I thought through the logic a bit more, then my intuitions were probably backed by underlying sound logic. However, this neatly highlights my point about this puzzle crossing the line over what should be included in a sudoku GP - the reasoning and deductions did not really compliment sudoku solving.

  3. Mark Goodliffe13 July 2017 at 11:20

    I spent ten minutes making little progress on the No-Touch, only to discover that I was actually using the Non-Consecutive grid. That was a real waste of time. I would have enjoyed the round more if I wasn't an idiot.


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