- 1 any row contains more than one number between 1 and 9.
- 2 any column contains more than one number between 1 and 9.
- 3 any grid contains more than one number between 1 and 9.
At the beginning of the game, the grid will have some numbers already filled in. We have to use the logic to fill in the missing numbers and complete the grid. Your move would be incorrect if -