Sudoku

The cell value and a Sudoku puzzle typically contain 9x9=81 cells,
Each cell can only fill a value. On an unfinished Sudoku puzzle,
Some cells have already been populated, while others are empty.,
Waiting for the solution to complete.
Row and column habits, horizontal line, vertical column, here is no exception.
The row is composed of a horizontal 9 cell, and the column is composed of a longitudinal 9 cell.
Clearly, the entire puzzle consists of 9 rows and 9 columns.. To avoid confusion,
Here, in capital letters and numbers, respectively, and column.
For example, the cell [G6] refers to a cell at the junction between row G and sixth columns,
It has been filled in with a value of 7. The term block refers to a specific position.
9 adjacent cell groups. In the image above, the block is alternately alternating.
Background color to specify. For example, for the upper left corner of the block, we are
Starting from [A1] block. Unit any row, column or block
Are a unit. Each unit must contain all but not repeat numbers 1 to 9.