Solve a 9×9 Sudoku. Each row of the board is 9 characters; a dot means an empty cell. Return the solved board.
Example 1
Input: board = ["53..7....", ...]
Output: ["534678912", ...]
Explanation: Fill the empty cells according to sudoku rules.
Output: ["534678912", ...]
Explanation: Fill the empty cells according to sudoku rules.
Example 2
Input: board = ["8..6.....", ...]
Output: ["876195342", ...]
Explanation: The second classic puzzle.
Output: ["876195342", ...]
Explanation: The second classic puzzle.