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To solve Sudoku using the backtracking algorithm, we can follow a ____ approach. The main idea is to try out different numbers in empty cells of the Sudoku grid and check if they lead to a valid solution. If a number violates the rules of Sudoku, we backtrack and try a different number.

Here are the general steps for solving Sudoku using backtracking:

1. Find an empty cell in the Sudoku grid.
2. Try out numbers from 1 to 9 in the empty cell.
3. If a number is valid (i.e., it doesn't violate the Sudoku rules), place it in the cell.
4. Move on to the next empty cell and repeat steps 2-4.
5. If all cells are filled and the Sudoku grid is valid, we have found a solution.
6. If a number violates the Sudoku rules or we reach an invalid configuration, undo the last placement (backtrack) and try a different number.

By following this approach, we can systematically explore different combinations of numbers until we find a valid solution to the Sudoku puzzle. Implementing the Sudoku solver algorithm in C++ would involve writing a recursive function that performs these steps.