How would a flowchart and/or pseudocode look for a function to check valid numbers, and a function to read the board look for a basic Sudoku program? Here is an example board from a text file:

 A B C D E F G H I 1 7 2 3| |1 5 9 2 6 |3 2| 8 3 8 | 1 | 2 -----+-----+----- 4 7 |6 5 4| 2 5 4|2 7|3 6 5 |9 3 1| 4 -----+-----+----- 7 5 | 7 | 3 8 4 |1 3| 6 9 9 3 2| |7 1 4