Friday Puzzle #172 - Classic Sudoku

[motris]

For those that haven't picked up my book The Art of Sudoku, this is the kind of tough, hand-written challenge you can find there. After writing enough sudoku I learned how to embed not only particular logical deductions throughout a grid, but also how to set up "Just One Cell"-like stopping points that really allow just one path forward. This puzzle was the hardest of the classic puzzles I wrote for the US qualifier, and in a speed competition probabbly encourages guessing, but it has a rewarding solving path to find if you choose to look for it. Enjoy.

Rules: Place a single digit from 1 to 9 into each cell so that no digit repeats in any row, column, or bold 3x3 region.



Solution