Performance in Sudoku

(tags game, puzzle, Sudoku)

I've been busy with Hudson's Puzzle Series Vol. 3: Sudoku for the DS. Really busy!

The above chart is my performance when completing all of Easy (やさしい) boards sequentially. It took me close to 26 hours to complete all 70 boards, and my average completion time is 22:15 minutes. The line in the graph shows the average up to a particular board. I suppose that Easy was really easy, since I completed the 70th board at 7:17 minutes. My rule is that if I feel like restarting a board, I manually erase it without resetting the time. Thus this is a true measurement of my attempts for each board.

I've turned my energies to the 140 Normal (ふつう) level boards. I'm already at board 41, but my average is approaching 30 minutes. Hm. 140 times times 30 minutes equals 70 Hours. Assuming that the Difficult level is fiendishly difficulty, with an assumed average of an 1 hour and 60 boards, I'll be finished with this game in another 130 hours, or less. The following graph shows my current progress on Normal, with 20 hours of total effort, an average of 28:59 minutes completion time, and a best complete at 11:03 minutes.

Sudoku has gotta a hold on me so I consulted the Sudoku page at Wikipedia, which filled a lot of blanks I had for programming a solver. Turns out that this my first time that I really wanted to check out a Donald Knuth book, because he describes a solving algorithm, Dancing Links, for which Sudoku puzzles are a specific case. I always assumed that just reading his seminal book series The Art of Computer Programming would be equivalent to doing a master's in Mathematics and Computer Science. They are that difficult! The wikipedia page seems to have enough information to adapt a solution in another programming language. Time to roll up my programming sleeves, maybe.

Ah my brain is mush. For example, another tab in my browser is devoted to Wayne Gould and Aki Hoshino's promotion of the PlayStation Portable version of a Sudoku type game, called Kazuo (カ ズオ official home page), found via Kotaku's "Sudoku Mastermind Loses to Bikini Girl". Too bad Kotaku doesn't fact-check as much as they like to post flamebait. Wayne Gould isn't the inventor, according to Wikipedia, but the main proponent for its popularity in 1990s in the UK, because of his computer-generated program. Wayne Gould couldn't be used to promote a Sudoku game, though, as explained below.

The Hudson's Puzzle Series Vol. 3: Sudoku is licensed from Nikoli, the Japanese puzzle company that took the original Number Place puzzle and added three improvements: only 32 givens (givens are the initially known numbers of a board), positional symmetry of the givens, and the name "Sudoku", from "suji wa dokushin ni kagiru" (数字は独身に限る). I found the advocacy page "A well-made Sudoku is a pleasure to solve" from Nikoli urging players to forgo computer-generated puzzles. The point was implicitly, Nikoli versions are the best. The relevant quote:

"Computer-generated Sudoku puzzles are lacking a vital ingredient that makes puzzles enjoyable - the sense of communication between solver and author. The best Sudoku make you concentrate, but aren't stressful. They are absorbing, never boring."

However that "pleasure" is all but gone in that Hudson's Puzzle Series Vol. 3: Sudoku, because at least the Normal level, you need to use the techniques that the author derided as "stressful". However, there have been times I felt that the difficulty in this implementation was ramping up in a clearly defined slope. I've felt like I've gone from a "full-course meal" (a board filled with many possible approaches and redundant info) to "bread and water" (a board where only one position can allow the solving to continue). I've had ah-ha moments where I felt "Ah they've decided to just use this technique now". Pretty soon I'll be just "eating bird seed", hah ha.

I'm definately at the crossroads now. Sudoku is "jumping the shark" for me. But I haven't even started a Difficult level board yet.

(edit: added picture of cover of Hudson's Puzzle Series Vol. 3: Sudoku, fixed s/g errors)