The sudoku grid consists of nine horizontal rows, nine vertical columns, and nine 3 x 3 blocks (also called boxes). Rows, columns and block are all kinds of unit. There are twenty-seven units in a grid. Every unit contains nine cells, and every unit must contain the digits 1 through 9. The numbers already in the grid are the puzzle’s clues. The numbers you add, as a player, are big numbers (as opposed to the small numbers you use temporarily, which are pencil-marks, and show the cell's candidates).
Cells that share a unit (row, column or block) are called buddies.
When you have an empty cell, the remaining numbers which could go into it according to the rules of the game are the empty cell’s candidates.
Rows are numbered 1 to 9, top to bottom. Columns are numbered 1 to 9, left to right. Blocks are numbered 1 to 9, in this layout:
| 1 | 2 | 3 |
| 4 | 5 | 6 |
| 7 | 8 | 9 |
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 Sudoku Kudos. As a programmer and a sudoku fan, I am in awe. Your sudoku software does sudoku better than any software does anything -- at least in my considerable experience. I refer not to the automatic solving so much as the rest of it. I also think the inclusion of choosing puzzle difficulty by solving technique is a stroke... it seems to me that your sudoku software does one thing, very, very well. Dave Jordan |
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