Puzzle #6 - by Wei-Hwa Huang
Solution of Puzzle #6 - 3 minute, 36 seconds
Puzzle #6 explanation
Two other pieces of sudoku business:
First, courtesy of thepiemansimon, I have completed the UK qualifying test. The first round had five difficult puzzles (including one nasty classic and one nasty diagonal) and took me 46 minutes. The latter round had twenty-four puzzles with none of them being particularly hard and took me 1h 22.2 minutes. This is just a hair over two-thirds of the time for a perfect score so again I meet my prequalifier goal of perfect score under time. Its odd to set a standard of hard puzzles on the round that limits participation (and which may encourage online solving tools as they were real nasty) and then to go to easier puzzles in the second step after you may have already chosen for something other than legitimate fast solvers. I hope Puzzler eventually posts it online for others to see, if just because some of the nations with the best qualifiers last year (France, Japan) are not doing qualifiers this year. My next practice tests may be the Russian from this year, as well as redoing the WSC1 and WSC2 puzzles.
Second, tied to their qualification apparently, the Slovak championship set a "world record" in sudoku of 5:25 and I only found out about this as someone felt it important enough to put on wikipedia. I cannot find this puzzle, which I am dying to see and solve in under 4 minutes, but I wanted to point out I already have two "world records" in sudoku so this is no new feat as the wikipedia competition section suggests. Also, without solving about twenty puzzles at one difficulty rating (which must be standardized by software), I'm not convinced any record is meaningful. If this is just the best time on one puzzle that is "hard", then I bet having ten more attempts at it would greatly improve the time for that whole room of competitors.