How do you implement a system for automatic Sudoku solution verification?

To automatically verify Sudoku solutions, you can implement an algorithm that checks three main conditions:

1. Each row contains the digits from 1 to 9 at most once.
2. Each column contains the digits from 1 to 9 at most once.
3. Each of the nine 3x3 blocks contains the digits from 1 to 9 at most once.

An approximate approach:

• Represent the Sudoku as a two-dimensional array int[9][9].
• For each row, column, and block, create a structure (e.g., boolean[] or Set<Integer>) to track already encountered digits.
• Iterate through all cells and check whether the rule of uniqueness is violated.

Example code in Java:

public boolean isValidSudoku(int[][] board) {
    for (int i = 0; i < 9; i++) {
        boolean[] rowCheck = new boolean[9];
        boolean[] colCheck = new boolean[9];
        boolean[] boxCheck = new boolean[9];
        for (int j = 0; j < 9; j++) {
            // Check row
            if (board[i][j] != 0) {
                if (rowCheck[board[i][j] - 1]) return false;
                rowCheck[board[i][j] - 1] = true;
            }
            // Check column
            if (board[j][i] != 0) {
                if (colCheck[board[j][i] - 1]) return false;
                colCheck[board[j][i] - 1] = true;
            }
            // Check block
            int rowIndex = 3 * (i / 3) + j / 3;
            int colIndex = 3 * (i % 3) + j % 3;
            if (board[rowIndex][colIndex] != 0) {
                if (boxCheck[board[rowIndex][colIndex] - 1]) return false;
                boxCheck[board[rowIndex][colIndex] - 1] = true;
            }
        }
    }
    return true;
}

This method checks whether the current Sudoku board is valid. To verify a solution, ensure that all cells are filled and the method returns true.